I spoke with a bio-scientist the other evening, and he emphatically stated that any true ENEMY of the USA who wished to commit bioterrorism simply would NEVER do anything like this. NEVER. It would be 100s of 1000s DEAD the first day.
I have occasionally wondered if some of the rabid animal-people who've burned down labs - I've wondered if they ever destroyed any building or complex or laboratory, from which they were able to remove a stash of this weaponized anthrax beforehand, and then no one realized it was missing because everything was gone, destroyed, there was no evidence of a theft, as there was nothing left to investigate.