I was going to disagree with you overall, but your list of issues stopped me - you're right, and those are very important items. That said, I would still disagree with the word "nibble" because of its strong trivializing effect. Rush, despite his flaws and significant omissions, is not trivial - his choice of topics is pretty regularly deep. I think, however, that he is subject to restraints few know about and even less acknowledge. As a result, he has to hit where he can, and keep his ammo dry for the rest.
OK...I agree with you. He has been a **powerful** force for moving conservativism forward. We are better off as a nation because of him.