Outside of Corfman, what was wrong with the other 3 scenarios? Societally, this was not inappropriate in that day and age.
If Corfman’s allegations are true, then Moore should step aside. However, her past behavior regarding false allegations is certainly fair game for evaluation. Not her sexual history, but her having supposedly falsely accused before.
As for proving his innocence, that is not possible, and it is the very basis for a smear along these lines. Only once the allegations have been supported by a preponderance of the evidence does the accused have to do more than deny. This is why the huge disparity between Corfman’s story and the other three matters. The other 3 allege no improper behavior.
Why not?
In this case, that's critical information.