I am having a hard time accepting a bioattack as a mainforce event. IOW the primary mode of attack. It's not violent enough and is too difficult to spin up into a full blown epidemic that will have the potential of spreading nationwide.
I think that the main event calls for extreme violence which will be easily documented for the inevitable photo or sound byte. Rivers of Blood sort of stuff. Violence on this level will be replayed around the world as a way to energize the base of terror. It has to be IMHO, a multipronged attack that has widespread effect, nationwide.
I agree, however there is still the lurking probings of hospitals lately.... Bioattack is outside of AQ's MO at this time. I'd expect a small scale test somewhere before placing a lot of time and resources on the line.