Yeah, that's nice, but if those back-dated votes were already mixed in with the main count, they can't be traced back to be invalidated.
This whole fight against fraud is happening two weeks too late. It needed to happen like that PA SCOTUS case, where they ordered suspicious ballots to be segregated out so they can consider the issues later and remedy it. Republicans should have got court rulings in place ahead of time in every swing state saying late or day-of ballots would be segregated out for inspection. Before election day I said the postmark stamps needed to be seized at close of business 11/3 and swapped out for visibly different stamps; this is why.
Winning a court case saying "they shouldn't have done that" doesn't matter if you can't fix the thing that was done.