The RFEF rules are quite clear on this, and Butragueño's defence that "we weren't informed about it" doesn't work since the list of suspended players was published to all clubs before the season started (and it wouldn't be a valid excuse anyway). Even if Flo treats Cadiz to some pocket money and they refrain from filing a complaint, any other club that's qualified for the next round could do it, and FCB/ATM surely would. Pretty inevitable.
Then again, stranger things have happened with RFEF