I think you're right, or at any rate, to the extent that this is not going to help the Dems, even if there isn't a major backlash.
I think what's going to happen is that it will all quietly disappear, because the Dems must surely realize that blaming a man who was in office for 9 months makes no sense when the guy who was in office for 8 years left a very clear paper trail of botched handling of terrorism in general, and Islamics in particular. They don't really want that examined too closely, I'm sure.
Their strategy is to hit and run. I think this will go away very quickly, probably not hurting them too badly, but on the other hand, not helping them.
What I wish would happen is that Bush would use it as an excuse to clean out the Clinton-era holdovers in the security services.