Well, there certainly was some sort of conspiracy going on, since anthrax was sent out to people.
Personally, I think that if there was some sort of a plot by upper-level people in the government to stage terrorist acts to influence public opinion, using biological agents would be the last thing they’d consider. Bacteria have a nasty habit of choosing their own agenda and spreading in uncontrolled manner. Chemical weapons are much more manageable, and explosives are even better (a few well-placed car bombs, for example). Still, nobody ever insisted that all upper-lever government people are necessarily sensible. . .
Since ABC isn’t revealing what information each individual source gave them, much less who those sources are, it’s impossible to say who got the media started on the whole bentonite angle. They referred to four separate sources, but did each of those four sources actually mention to bentonite? Or was it only a few of them, or only one, who mentioned the bentonite? And how many of those sources who mentioned bentonite would have been involved in the testing of the samples, and if they only heard second-hand about the reports of the test then who did they hear those reports from?
It’s possible that Dr. Ivins was one of ABC’s sources, and that it was from him and him alone that they heard about bentonite and thus got onto the whole Iraq idea. Or ABC’s sources could have been told by Ivins that the samples tested positive for bentonite, and they passed the word on. In which case Dr. Ivins (assuming he really was involved) could have been the only person at USAMRIID who was involved. Or there could have been a dozen people there involved.