Nobody would be questioning Tre if we hadn't literally seen him on the practice field for the last three weeks. Also, let's face it, he's a likable guy, so he gets the benefit of the doubt that some other guys might not.
If he's still injured and could make it worse by playing, then say that. If the team thinks they're better off with him not playing because his rehab went poorly for whatever reason and the guys on the field are still a better option than he is, then say that. If he's not injured and is a better option than what we have but he's still holding himself out, then say that. The vague "he's not ready" excuse will fly for two or three weeks. OBJ was medically cleared last week and wants two weeks to get into game shape before making any decisions. We're past that with Tre and it's time to either come clean or play.