My solution would have been to pay him, because watching that $30M+ of cap space on the field today was no fun at all.
Still, jam tomorrow, eh?
I would have been fine keeping him and signing him before all the excrement went down. Granted, that also would send a message to the league - whine about your contract with the Jets, and you'll get a raise. We don't know how much money Jamal wanted.
But there's no guarantee that would made made everything better, especially once he demanded the trade.
Once he goes public with the trade demands, we don't know if he would have resigned. He demanded a trade. Those don't always get immediately resolved with a contract. Some do, some don't. If the place is as bad as you (and he) say it is, why would he resign?
Second of all, even if we did sign him, why would we expect him to all of a sudden fall in line? If we went 6-10 this year, he'd probably still try to force his way out in a trade in March. He tried to get to Dallas last year at the deadline. What would stop him from trying to get to Dallas next offseason?
I wanted to make it work with Jamal. But when you can get two 1st-round picks, a quality replacement, an upgraded mid-round pick, tons of extra cap space, and you alleviate your roster of a headache, I think you had to do it.