I personally believe that the AWB ban portion of the bill is a sacrificial lamb, in order to make the rest of the bill seem very unobtrusive. They would certainly love it if it passed, but they're willing to offer it as a bargaining chip. The optimal outcome is if *none* of it passes. Even the universal background checks is worthless if all guns aren't registered, and they know that. So the next round, they'll say "in light of NEW unpredictable disasters, we now need to register all firearms so that the system will be more effective". Exactly what they're saying now- they will never change their tune, and we know that.
Generally speaking holes in anti-gun theories are called "facts."