Resigning requires feeling shame for your actions. Vance has absolutely no shame.
Keep in mind that his private communications have leaked. He talked about what a monster Trump is for making immigrants feel unwelcome and unsafe.
Vance is not like Trump. Trump was raised to be a monster and not intelligent enough to question anything. Vance, OTOH, is smart enough to know better. He chose to be this person. He willingly, voluntarily sold his soul to the MAGA devil. That’s why looking at him and listening to him makes people’s skin crawl. There was a person in there once who was forcibly evicted in favor of a monster.