Tim has the best deadpan in the NBA. I think he's very funny in the locker room. I love the deadpan as a comic tool and he's excellent at it.
As far as your statement, I fear you are probably correct, but I hope you're not. I think if Tim wanted to be, he could be an excellent head coach. He understands the game at a near genius level tactically, he's very good at keeping an even keel between wins and losses, he'd have the respect of his players, and unlike most superstars, he'd have no problem coaching mediocre players because he never acted like a star in the locker room.
I've always said that of the big three that Tim would make the best coach, Manu would make the best GM and Tony would make the best owner.