I am not a security expert, but my thoughts are that "Anonymous" isn't really hurting anything.
1) An article from The Guardian speculating that Anonymous might be doing more harm than good does not equate to national intelligence agencies complaining that Anonymous is doing more harm than good.
2) If intelligence agencies are watching Twitter accounts for covert intelligence, that is idiotic. Twitter posts are public, easy to find, and unencrypted (I suppose you could hide a secret message in a Twitter post, but anyway...). It seems to me that the Rickrolling is perfect for disrupting ISIS sponsored Twitter recruitment accounts. When it comes to actually planning attacks, I imagine this makes no difference whatsoever--that is more likely done by ISIS on encrypted non-public channels that the intelligence agencies are trying to find and decrypt.