I personally like 14H4–Player with fallen flag may not claim. if for no other reason than its simplicity and bold font that is easy for parents & players to understand. Now, the rub is that it is specific to ILC, but the intent and spirit of that rule is often extrapolated to cover other situations (especially now that delay clocks are making ILC all but extinct), and I feel that a flag fall vs. illegal move correction is one of those situations.
{btw-yes, in my situation, Player B had about five seconds which elapsed in which he could have claimed. I also find the notion of a player winning via an illegal move distasteful–almost a deliberate ‘blitzing out’ of the opponent, and contrary to 11D1, where an illegal move is not corrected if two moves have elapsed or the game ends in checkmate/stalemate with a legal move. None of those are relevant to a game ‘ending’ via time forfeiture upon an illegal move, hence the confusion.}