The thing with CJ is this.
Are you going to sign him after this season. Probably not.
Will you trade him midseason? Maybe. And really the only way you would trade him is if he is doing poorly, which is where he would be right now. If he is doing well, you keep him for the run since he does have experience.
So where would he have more value. Now, when a team that trades for him could recoup a draft pick if they give him a QO. Or later in the season, if he's floundering. Because I really don't think we will trade him if he is doing well.
So IMO. Your options are, trade him now, save some salary, and possibly get something in return. Gamble, and hope he recovers from the surgery, and you will have a postseason starter. Or wait, and find out you have to pay most of his salary, while costing you games, and get little in return.