The deduction that because Anonymous hacked Palin's e-mail, anti-scientologists were responsible for it isn't valid. The only thing you can conclude is that Anonymous hacker is Anonymous, and nothing more.
Anti-scientologism is just a fling for the lulz for the core of anonymous anyway; most of the Anonymous resistance to Church of Scientology consists of new "recruits", so to speak, with only partial or no real knowledge of the Anonymous history... and they see the Anonymous primarily as a way to oppose CoS namelessly without considering that anything done namelessly is, in fact, a part of what Anonymous does. The point with Anonymous is, if hacking Palin's account provides sufficient lulz, someone does it. Anonymous has been adopted as the description for the nameless nonorganization that attempts to bring CoS' misdemeanours to broad daylight for obvious reason of CoS attempting to discredit and harass anyone who puts a name behind the opposition, and I seriously doubt those Anonymous had anything to do with Palin's account being hacked. It isn't, like you said, in their interests. Some Anonymous do vandalize CoS assets in the internet, but that doesn't really affect the rest of the anti-CoS Anons.
Some people see Anonymous as the crusader uniform to wear when resisting perceived wrongness and evilness in the interwebs. Some use it just for trolling and to produce lulz.
And most likely scientologists use the name in attempts to stage "The Anonymous" as a cyberterrorist organization or somesuch. They fail to understand that in reality, Anonymous is anything but "The". Anonymous cannot be classified as anything, because of it's non-organized, non-centralized existence. Every part of anonymous is independent and the rest is not involved in the actions of one part. It just is, as long as anyone uses it.
Like you said, it isn't in the Anonymous anti-scientologists' interests to hack Sarah Palin's e-mail account. Either one of them had a complete different motives for it than opposing scientology, or it was some other Anonymous with no ties to anti-CoS movement. Or it's CoS trying to make damage in the name of Anonymous in order to somehow sic the government on the "Anonymous organization" by proving it to be a dangerous (even terrorist) organization. These are the guys who did manage to take a comment about "[Tom] Cruise Missile" into court and the commenter convicted of illegal threat or something like that. They use everything they can against their opposition when they are declared "fair game". And if there isn't anything they can use against opposition, they fabricate or manufacture something to use against them. So of course they would go and cause harm as "Anonymous" to get "Anonymous" into trouble.
They actually filed an "injunction for protection against repeat violence" against "Anonymous" to prevent them from protesting on the street in front of their centers. And it was denied on the basis that the appropriate part of law doesn't apply to corporations, not because it would be totally retarded to grant a restrainging order against anonymous to paranoid, paramilitary, paranormal cult...
