I figured The Beltway snipers using the Bushmaster would have been enough; notice how fast the main stream commie press dropped the whole issue when they found out the guys who did it were a Black Muslim and his butt boy instead of some crazy, rednecked white supremacist? If anything the fact that these guys had sympathy with MOOOslim Terrorists, and that the random sniping was right out of the Al-queda playbook, was a lesson that maybe, just maybe, a well-armed citizenry was a good idea. That's why the commies don't bring the episode up as a 'poster child' for gun control.
Another reason for this incident not getting traction with the anti-gunners is that the rifle used was undoubtedly a post-ban gun. It was probably missing a bayonet lug, a flash suppressor, a grenade launcher, and a collapsible stock. It probably had a pistol grip.
The anti-gunners could have found themselves having to explain how the AWB failed to regulate what they are claiming justified the law. Further, they would have to explain how relevant the military features and appearance of a rifle fired from hiding in single-shot mode would contribute to the sniper's success. There has never been a hunting rifle made that would not have been just as effective.