If someone doesn't like you for any reason, they can block you on PSN, preventing you from being able to join any room they are hosting, permanently until they unblock you.
I'd been kicked from a room once before for no reason, went to rejoin to ask why and I got in perfectly fine (before promptly being kicked again and receiving a message saying "GTFO"
So it would seem the room doesn't need to be closed for you to be able to join again, it's just blocking that results in that. Unless I just had an "odd one out" situation, since that's the only instance of being kicked out I've experienced
Whats "GTFO" ?