The fumed silica (Cab-O-Sil) was, but remember, any formulations chemist worth a crap who was familiar with aerisolizing an active would have known to use it. That technology is increasingly common as the drug delivery industry moves toward getting rid of needles (fear of HIV liability associated with needle-sticks of doctors and nurses). That's why patches and inhalants are so common these days.
The biologists who understand handling anthrax probably don't qualify to aerosolize it. It therefore means NOTHING that the FBI guys weren't able to replicate the Senate anthrax without an analysis of the project, its personnel, and its available tools. It could just be another stupid government SNAFU.
The silica coating technology for inhlational drug delivery is not that common. I don't know of any US products that plan to use it - the DPI (dry powder inhalation) players in the US are mostly relying on creating hollowed out spheres of drug (eg. insulin) to stop Van der Waals clumping.
However, there is a group in Germany that are experimenting with silica: http://www.mvt.uni-erlangen.de/Personen/MLinsenbuehler/Forschung.html
Note how difficult it was for them to coat lactose particles with silica and not simply end of with a messy mixture of lactose and silica.
Look at the SEMs - each lactose particle has a perfect coating of silica. There is no sign of any extraneous silica or secondary phase. They had to go to great lengths to achieve this - they oppositely charged the silica and lactose and mixed them in liquid nitrogen. The charged silica was attracted to the oppositely charged lactose. There are other ways of doing this as well. The point is - it's not easy.
Geez.....this looks to be a huge effort.