Lots of people have asked how the GOP squares this with Federalism.

But how do they square this with originalism? Do they think the founders meant to give one man veto power over whether to accept state electors but just didn’t word it all that clearly? Keep in mind that back then VP wasn’t even its own office to be sought, it was the loser of the presidential race. But they gave him veto power over state-chosen electors? That’s what South Carolina and Virginia etc. thought they were ratifying?

What do they make of the fact that the framers themselves never behaved like they had this power? Both John Adams and Thomas Jefferson were sitting Vice Presidents when they themselves were on the ballot for President, after all.

I’m beginning to think this theory is a little ad hoc...

The entire presidency has been ad hoc. They've gotten into the habit of following him and they can't help themselves on this one.