What exactly did he do that makes you think he's a liability in the half court? He doesn't dominate the ball or force shots, nor is he a turnover machine. And, he's as good a passer as we have. Which isn't saying much, but is still worth something when being compared to his teammates to determine playing time.
If anything the knock on Pointer is that he disappeared in some games, deferred too much, and became invisible. But generally speaking Pointer gets other people involved and only takes high percentage shots. That's pretty much what I want from my 3rd option on offense.
Greene on the other hand is a guard who can't shoot, pass, or drive very well. It's really not a stretch to say anyone on the team could fill that role.