I’m surprised at you.
You ought to know perfectly well that voters vote for Electors which have been chosen by the Party to support a Nominee.
The ballot may be printed with someone’s name on it, but if Joe steps out at the last minute, the voters can still vote for the same Electors to support the same Party. The nominee can change at any time no matter what the ballot says.
Yes they can CHANGE THE NOMINEE BUT NOT THE BALLOTS.
It doesn’t matter if the ballots can’t be changed. Impossible to cheat at that point because 1/3-1/2 of all ballots are out with Rutabaga’s name on it.
So now you split the vote? Trump wins by 400 EVs? Yes, the ballots are critical, esp. since the “2000 mules” depended entirely on early and absentee ballots.