My concern is that red states can use Trump's fraud claims as a pretext to throw out their results.

If enough states throw out their votes and no candidate gets 270 electoral votes, then we have a contingent election in the House.

In a contingent election, congressmen cast votes for their state, but each state only gets one vote regardless of its population. Because there are more red states than blue, Trump would win.

A contingent election is Trump's only hope of actually winning in a way that is technically legitimate. He will try as hard as he can to make that happen, and you can already see him preparing for it by claiming that there will be massive fraud.