They're not. I recently returned from the Eastern Fishing and Outdoor Expo here in Massachusetts. One of the knife dealers had AOs on display, along with a working model equipped with an unsharpened blade for safety reasons. He demonstrated to the attendees the way the knife worked. One of the people there was a Massachusetts Environmental Police Officer in uniform. These people have even more power than the State Police, since they can arrest for ALL offenses, not just fish and game related ones. The EPO remarked how handy the knife was and that he was thinking of getting one himself. If that knife was Massachusetts-illegal in any way, the EPO would have enjoyed an easy felony bust and the dealer would have been paraded out of the DCU Center in handcuffs!
Ah, that's very good to know. I only make my remarks before based on what I could read, and was concerned about getting the asker in trouble should I be wrong.