Something unbelievably poetic about Dio trying to appeal to him with how he'll be immortal, how he'll be able to live forever healed to live with Erina; Only to belatedly realize that he already accepted his death
It's the truest affirmation of his own humanity in contrast to Dio
Dio realizing "holy shit he's dead for real" and immediately dropping the villain act is one of the best scenes in the entire series, he really thought they'd be going back and forth forever