Bullshit, man.
If all else were equal, the GOP would have looked at those results and said "Damn, there's a lot of potential there, we should really be chasing that vote". Instead they're not doing so, in fact they seem hostile to doing so, and you're trying to defend their reasoning as some cold political calculation that has nothing to do with hostility towards any outreach to those voters that would actually give them something.
Here's a good question: what, other than lectures or hostility, could the GOP reward a surging young White male vote with, that wouldn't be torn out of the hides of other factions that fund or otherwise control the GOP?
Would Vivek be all smiles at hearing that the GOP was getting a massive amount of young White male votes by promising to gut the H1-B program and make it easier for those White men to get high-paying tech jobs? Would he, or the group he's closest to, be enthusiastic at seeing the GOP crushing Democrats while providing that? Or would the reaction be horror?
Now take that and run similar scenarios with Jewish interest groups, or basically any other group.
To appeal to young White men is to make less room at the table for other groups, because their interests will clash.