The smart player.
He can sign the extension two seasons before it even takes effect. That is security against future injuries and even against bad performance. Oh, and it will be about a quarter of a billion dollars. Other teams can't provide that security since he would have to wait another two seasons to sign with a new team.
If he wants out he will sign the extension, play the first season of the extension since he can't be traded that year, then demand a trade.