Speaking from experience in Arma... the majority of the public users in TS come from within a game and aren't even registered on the forums unless, for instance, they need to request flight/mhq rights.
Locking down TS entirely seems like it would turn a headache into a migraine since it would require directing our "game-only" guests to the forums to register here before they'd be able to join us in TS.
My $0.02.