Suspected != guilty and if they go around publicizing suspects or even people who the police have named as suspects or "persons of interest" who turn out to be innocent, it will hurt Anonymous's own reputation big-time.
What they - and everyone else - can and should do is make sure that if you do run across child porn or links to what you think is child porn, you immediately report it to all relevant authorities and that if the authorities seem to be ignoring a case, that all relevant news outlets are notified. If the news outlets seem to be participating in a cover up, notify other news outlets, but be careful: What looks like a "news outlet conspiracy of silence" may be because the FBI is in the middle of a sting and the feds have asked the news outlets to keep quiet until the trap is sprung. If Anonymous's well-meaning attempts to bring things into the open result in the sting being aborted or going bust, well, that would be bad.
On a side-note:
* Do not go "looking for" child porn - you could wind up being charged and convicted yourself. If you are wondering what it's like, my best educated guess is it is like looking at images of concentration-camp children: 1) the underlying event that happened to land on camera haunts the person in the photograph for his or her life, 2) the image itself is likely to be so stomach-churning that it will haunt you for a long time, and even if it doesn't, 3) the knowledge of what happened to that child should haunt you for a long long time (if it doesn't, either you have grown jaded and I'm sad for you, or you need to talk to someone because your conscience may be less than that of the average adult's and this diminished conscience may lead you to hurt someone without realizing it and/or without caring)
* If you routinely do things in your fight against child-porn that put you at a higher risk of running across it, as some of these Anonymous guys likely are, take technical steps to reduce your risk (use a text-only browser, for instance), and have a lawyer on retainer. Ask your lawyer what steps you need to take so when the police do come knocking it's painfully obvious to the police, the jury, and to everyone else that you are not intending to actually download or possess the stuff but sometimes it gets through your technical barriers.