[TWC said there is a 140 mph jet stream, the air is turbulent. Being denied the request for a change of course sounds like an issue.]
IF he detected severe weather on his radar, requested vectors around it, and was denied due to traffic conflicts this could be a major FAA problem. He could have declared an emergency and changed his heading but if this was IFR it would be a serious violation and he probably thought he could tough it out. The first rule of flight is that the pilot in command is responsible for the safe outcome of the flight but it would be a tough call to make if he did not have visual separation.