Perhaps you are unaware that some colloidal silver products out there produce silver particles as small as 0.65 nm? That is just over twice the size of a silver atom and likely even smaller than your claimed particle of one silver atom bonded to three oxygen atoms.
Actually his product would be larger. Silver trioxide alone is Ag2O3. So two silver atoms along with three oxygen atoms. On top of that he also claimed it contained a little hydrogen.