Hi. Post-Liberal here. This is not correct. The actual Post-Liberal criticism of liberal principles is that they are:
1. Not universal
2. Corrosive to all non-chosen obligations, numerous of which are necessarily illiberal constraints for society to function at all.
Non Universality
The instinct since the aftermath of WW2 was to universalize humanity. It was differentiating between peoples and placing them upon a hierarchy of value that allowed the Nazis to justify their ultraviolence and therefore with this being the new foundational myth of our societies this differentiating was exemplary as the ultimate evil, with its opposite, naive universalism, upheld as the ultimate good.
Liberal values were thus assumed to be universal. Everyone must want to live like Liberals because ours is obviously the "best" way to do things. We are the freest. The happiest. Everyone years equally to be free and happy. Our way produces the most freedom and happiness, therefore our way is best and everyone must want to live our way. To the extent they do not or cannot it is the consequence of tyranny being imposed upon them.
Particularly after defeating the Soviets in the Cold War, Liberalism stood alone as the champion of the 20th century. Fascism and Communism were defeated. With no great ideology to offer a counterexample, Liberalism was the default, and it was natural that the rest of the world would want to follow suit and Liberalize.
This lead to Fukuyama's "End of History" and many egregiously bad decisions born from a "Strategic Narcissism" which presumed a universal appetite for Liberalism and its ideals.
We jump started China's economy with offshoring under the presumption that closer economic ties would liberalize them. Instead they became richer, more competent, and techno-fascist, and are now our number one global rival.
We invaded Afghanistan and Iraq with the deluded idea that we were going to "spread democracy" which is to say "spread Liberal values and systems," only to find that there was no genuine appetite for these things in these nations, and that the population would rather fight against Liberalism than for it.
We imported obscene numbers of foreigners, in particular from those same regions which rejected the imposition of Liberalism, with the expectation that in living among us they would come to live like us, but this could not have been further from the truth. Far from embracing Liberalism or a Liberal life style, these imports are actively contemptuous of Liberalism, view us as naive morons, and actively seek to subjugate us and impose their values in Sharia.
Far from being universal values, a Liberal lifestyle is the natural state of affairs for a small minority of North West European societies ("WEIRD" Nations). Liberal norms are well-suited to these populations for whom these norms are effectively a codified expression of their default ontology, while being as alien to foreign populations as Sharia is foreign to us.
Post-Liberals therefore reject the universalist instinct of our current societies. It is so taboo to recognize material differences in cognition across populations, not merely in a general intelligence sense but with respect to societal norms and preferences, family structure, etc., that to do so is to risk serious reputational damage by a cult dogmatically committed to upholding the Universalist ideal in direct contrast to the deluge of evidence that suggests the contrary.
However if Liberal ideals and norms are to survive anywhere they must be protected from external subversion; subversion only possible because Liberalism is incapable of rejecting its Universalism and safeguarding itself from peoples who are not willing or capable of adopting it earnestly.
Corrosiveness to Unchosen Obligations
The Liberal instinct is described in Post-Liberal circles as a "universal solvent" because the Liberal instinct is naturally one of permissiveness. There is no rule or boundary or taboo that Liberalism will not gradually chip away at because the Liberal instinct is fundamentally to say "why shouldn't I get to choose?"
And this will eventually apply everywhere and anywhere. Much of the early success of the United States was not attributable to Liberalism. Rather the cultural legacy of Christianity did a ton of heavy lifting while early Liberalism did legitimately remove particular excesses of older Monarchical systems which combined genuinely yielded fantastic results.
But Liberalism has no internal capability to determine when it has "gone too far." Liberalism cannot determine for itself why Chesterton's Fence is there, it can only determine that the fence is a restriction on its ability to choose to venture further for itself, and so it works to remove the fence. Sometimes post by post. Sometimes all at once. But in either case the other side of the fence was a fatal abyss.
This means that Liberalism has in itself the architecture of its own annihilation. Because gradually over time those obligations to each other, to one's family, to one's nation, etc. are challenged and eroded until a coherent concept of the nation itself is eroded.
Even the unchosen realities imposed upon us by nature itself are rejected in favor of the right of the individual to choose, which becomes the basis for the trans insanity. And on that note, naturalization of foreigners and proclaiming them to be "just as American as us" is no different, for nationhood is a pre-political reality of ones birth immutable in all ways, and certainly not by pen.
Post-Liberalism therefore recognizes that the unconstrained Liberal instinct is self-destructive and will sacrifice any and all good that Liberalism was able to generate in favor of the dissolution of itself as the ultimate manifestation of its own telos. Like an expanding bubble gradually putting pressure upon the surface tension of the soap until it annihilates itself with the removal of all constraints.
Preventing this thus necessitates the reimposition of some degree of boundedness on the Liberal instinct. We do have some unchosen obligations that are both necessary and desirable and Liberalism will actually do infinitely more harm than good if it cannot be contained within some kind of boundedness of higher principles that can veto Liberalism's singular maxim "I must be able to choose anything" with the implied "no matter how terrible."
Far from being a threat to the basic Liberal norms expected by actual Americans, Post-Liberalism is a necessary safeguard to preserve the good about Liberalism (i.e. those norms and freedoms which are typical of the North West European WEIRD nations and their colonial offshoots, free speech, etc.) where those things will otherwise be lost in perpetuity if no boundaries can be redrawn (either to Race Communist Technocrats whose ideology cannot survive the free flow of information for its incongruity with reality, or to Islam and its explicit program of religious subjugation and the imposition of its Sharia norms).
If you actually care about the norms and traditions of historically Liberal peoples, Post-Liberalism is virtually the only strand of contemporary thought that has a realistic possibility of conserving and sustaining those freedoms.
The “post liberal right” believes that the classical liberal principles of our founders and the Declaration have failed and need to be replaced with a new order that elevates the “common good” above individual liberty. That should be disqualifying for anyone hoping to lead this country.