It is not our job sort out who is on the team. By allowing him to participate in the activities, the team/coach has made that decision for us. Being on the floor warming up with the team, he is participating and will get a T.
Now the only question that remains is whether to add them to the book as a squad member or just penalize him as bench personnel. If the former, you might also have an administrative T for changing the book.
(I suggest the latter)