I'm not surprised that these question shave come now. When BA challenged the vote it can only have been (in my personal view) because they could show the figures of crew who asked them to deduct membership fees from pay and compared it against the numbers who voted. Unless the two tallied within a very narrow margin - the vote would be invalid.
Thus, when BA quietly waited until the last minute (.com) and pitched the numbers across the table to the judiciary, fallout became inevitable. It appears to me (personal view) that BA have won this round and, just possibly, initiated a turning point in the affairs of the whole shooting match.