I didn't realize you hadn't seen it. Now I know why we were talking past each other. Anyway, I don't know exactly how "advertisement" is supposed to be interpreted in this sense, now that you mention it. I figured it probably meant any open, public statement, but
Bouvier's Law Dictionary defines it as, "A 'notice' published either in handbills or in a newspaper." Granted this definition was pre-radio, but still, it seems that violation of a law against some form of "advertisement" would have to come under the laws of libel, rather than the laws of slander.
Maybe my initial reaction was right, and this story's bogus.
Regulating commercial speech is far less worrisome, imho, than regulating all speech. The former is probably defensible, the latter clearly abridges the 1st Ammendment. I suspect the prosecutor goofed, or the story is bogus.