The thing is, if we are trading for Asik, then that signals that we are at least going to begin trying to compete. If that's the case, then I have no desire to trade Green, 1) because I am not sure it's worth it (others will disagree) and, 2) Houston really has no need for him.
If we are going big time and trying to acquire Carmelo for the sf position, then I can see doing this, but otherwise it leaves us with a huge gaping hole at sf instead of the one we already have at c...and the c we are getting isn't 'that' amazing.