In time Max will of course let us know, in the meantime it is wrong of you to assume what he feels regarding members only posting either way. As far as I can remember the only clue available is in a post from Joe Offer saying that AT THAT TIME Max was not convinced of the need for this.
It's my guess however, that during the course of the many ensueing rubbish threads started by Guests, along with the nasty comments contained in other threads by them, he may just have changed his mind.
Members only also means that controlling the ingress of undesirable posters is a more exact science.
Giok