They're just repeating nonsense from The Washington Post. That information was "discredited" by a letter to the editor explaining that images of the attack anthrax indicated it did NOT contain fumed silica. And the spores were certainly NOT COATED with fumed silica.
That Washington Post article by Gary Matsumoto and Guy Gugliotta was preceeded by another article involving Gary Matsumoto which said,
Four well-placed and separate sources told ABCNEWS that initial tests detected bentonite, though the White House initially said the chemical was not found.
The first battery of tests, conducted at Ft. Detrick, Md., and elsewhere, discovered the anthrax spores were treated with the substance, which keeps the tiny particles floating in the air by preventing them from sticking together — making it more likely that they could be inhaled.
That ABC report was totally "discredited" AND disproven by the fact that aluminum was not found in the attack anthrax, and therefore it could not contain bentonite -- even though Gary Matsumoto briefly tried to convince people that it may have been "aluminum-free bentonite."
And then, of course, there was another article in Science magazine where Gary Matsumoto reported that the attack anthrax contained something else:
About a year and a half ago, a laboratory analyzing the Senate anthrax spores for the FBI reported the discovery of what appeared to be a chemical additive that improved the bond between the silica and the spores. U.S. intelligence officers informed foreign biodefense officials that this additive was “polymerized glass.”
Yet, AFIP evidently never noticed the "polymerized glass," since they neglected to mention it. I've asked you before, but you've never answered this question:
Was Gary Matsumoto writing nonsense when he said there was "polymerized glass" in the attack anthrax, or did AFIP totally screw up when they failed to notice it?