Isn't "Anonymous" anyone who claims to be it?

You must work for congress, quick, lets make being anonymous illegal. That'll stop this!

Within reason. It's anyone within the Anonymous subculture that claims to be it.

There is no way to tell if someone is credibly "within the Anonymous subculture" and "Anonymous" "releases" conflicting "press releases" with some regularity. There is no organization to "Anonymous", it's just an MSM-manufactured boogeyman to represent any teenager and/or groups of teenagers which knows how to send a lot of requests to a website simultaneously. samstave is also correct that those in power relish this since it gives them a lot of latitude to scare the commoners and get better tracing tools in place.

There is no better example of the No True Scotsman Fallacy.

No, that doesn't apply here at all. There's no (public) definition of who is or isn't Anonymous.

Sure it does. No true scotsman breaks down to a claim that some group has some Trait, then claiming that because some individual does not share the Trait they are by definition out of the group. I guess sometimes it's valid, but not here. Anon hasn't shown itself capable of an attack like this and if you look at the attacks by anon on scientology you'll be left wondering they were able to form a group identitiy with their fringe (core?) As it is.

Palish might be right that this doesn't sound like its from any of the main group.