Two different concepts.....dress code for safety as opposed to dress code for community standards, but we already do have alcohol limiting in both the QP and on board. It's RSA and is left to the discretion of the staff.
A better analogy would be to compare a member of a club which bans the consumption of alcohol, turning up with a six pack and demanding "their right" to consume it in that club. That would be against the rules of that club to which the member agreed to when joining. Similarly, a person turning up to a QP in a level of attire which is deemed beneath the level accepted by the club and demanding access is breaching the rules to which the member has agreed to be bound by.
I think the only point of dispute is whether or not QF are clear enough with what they deem to be acceptable standard of dress. Perhaps they realise that too, which may be why they are clarifying it now.