It's true that security wasn't great. But for a far-left group to arrange for the theft of professionally prepared material whose very existence was being kept secret is difficult to believe. It's easier to believe that someone could have obtained Ames anthrax prior to weaponization, but then one has to believe that your hypothetical left-wing group has laboratory facilities both for inventing and for carrying out the weaponization process, in an entirely clandestine fashion. That's quite difficult to believe.
2. Why Leahy and Daschle ? IF this was a "far-left" protest,the plotters may have been fairly sure neither man would actually be EXPOSED to the anthrax letters.The September mailings had put the nation on notice,and special precautions-meager as they might have been-were being taken. Daschle and Leahy would (and I'm sure did) perceive the letters as some sort of right-wing plot.
Why attack even the staff of two of the government officials most friendly to you?
If the purpose was to convince people that it was a right-wing plot, why did they try so hard to convince people that it was an Islamic plot?
There's also my third question, which you didn't answer:
"Wouldn't a bioterror attack be expected to result in a resumption or resurgence of biological warfare research, and isn't this the precise opposite of what these people wanted to achieve?"
What did your hypothetical perps want to achieve that they thought they could achieve through the anthrax mailings?
I think Occam's razor suggests that something else is the right answer. Everything in this theory seems strained - no offense intended, I agree with you that we should consider all sorts of possibilities, I just don't think this one works on close inspection.
John, picture this scenario: a young dedicated female intern
who has been gulled into thinking she's doing the right thing,scouts out the location of some (supposedly not-there)vials of LIVE anthrax,pulls one vial,and substitutes an identical-looking vial of harmless simulant.
She hides the vial long enough for it to warm up to room temperature,then smuggles it out-under a sanitary pad - a method long used by cocaine smugglers by the way.
There is no need for a lab.All that is needed is a proper glove box-which can be bought or built.