If BO is found to be Constitutionally ineligible AFTER the States have certified their results, then when the votes are counted in the Senate, both for President and Vice-President, BO’s will be ignored, and only Joe Biden will have a majority, and will be elected. The interesting thing here is that under the Constitution, Article 2, Section 1, in such a circumstance, John Mccain would become Vice-President.
Check out Article 2, Section 1. It’s a bit confusing, but clear enough.
If BO were to be found ineligible BEFORE the States certify their votes, then I agree, the States would generally be free (within the constraints of each State’s own laws) to instruct it electors how to vote.
There is NO circumstance here which could result in a delay to the swearing in of a new President.
Well Joe Biden always said he wanted to be on John McCains ticket!