In the first place, you don't know that no one has accused them. From what I read, the cops as much as did so. Are you following the media reports? Did you see the Today show article and vid? In my view, it is fair to say they have been accused. And there's certainly a lot of people here accusing them, directly or indirectly...you could be said to be one of them, in a way.
Secondly, having a lawyer to advise you is never a bad thing, really, especially if you are innocent. Among other things, a lawyer might be able to tell them how far they can push LE, whether they have to accept LE's strategies, and what other kinds of things they can do on their own to help search for the child. A good lawyer can also help smooth communications, by providing a less emotional voice between the various parties.
There are some sleazy lawyers out there, no doubt. But it is very unfair and narrow minded to make blanket assertions that imply someone must be guilty if they hired a lawyer. I had a client once whose child was abducted (case got a lot of publicity, she was released unharmed at a mall the next day). I was one of the first people he called. His family were also 9/11 victims. Sometimes people just need some good help and advice.