The AMA got in bed with the FAA a long time ago, at least they thought they did. They wanted their membership to have a carve out from the federal registration, now that they have to participate like the rest of us second class citizens they're complaining about it. I doubt they have the balls to challenge the FAA.
The fastest growing, actually the ONLY growing segment in RC is FPV racing. Go and try to do FPV racing at your local community based AMA field. The AMA has their collective heads buried so far up their a$$ they have restricted the one thing that would have provided them with the potential to grow. The AMA looking into the legality of the rule? How so? Development of the Registration rule did not go through the NPRM process and last time I checked Christmas didn't constitute an emergency.
Its also interesting that the FAA reported that over 181,000 drones have been registered as of the start of CES. That's interesting on a couple of levels. The AMA claims that they have approximately 180,000 members that they sent notices to their members telling them not to register. So that would indicate that apparently there are more people flying RC than are AMA members, or the AMA members ignored their suggestion to hold off registering.
Also what happened to the "emergency" because the FAA expected 1M drone to be sold last Christmas? And only 181,000 have registered? Were the majority of those drones sold under half a pound? This registration wasn't just for the drones purchased this year but all drones and the FAA is patting itself on the back because they think 181,000 is a high number.
Maybe, just maybe the threat that drones represent to public safety and privacy are a tad bit OVERBLOWN!? The numbers have never added up.
