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I am remembering this, so it may need massaging in details, but if I remember correctly, the use of substances like bentonite or kaolin in biological weapons is to facilitate the particles sliding by each other so they won't clump -- during the explosion of a bomb device. Pollen is plenty rough on its edges (required by most bee legs), and aerosolizes just fine in air currents, as do lycopodium spores, which are also rough, and frequently used in science classes to form colloidal suspensions in air which are then exploded to demonstrate [take your pick, mining disasters, grain elevator explosions, etc.].
A second note, not that bentonite is really relevant anymore except with Brian Ross, it is a key ingredient of kitty litter. For this reason many persian cats have been under surveillance since 2001.