Protection and due process
Why can the AGs not just write up a subpoena, it is not a hard task for them to do. All MySpace are doing is protecting themselves from legal action should data be given. You cannot expect any company to put themselves in a position where they are open to being sued by any group or individual who's data they give to law enforcement agencies.
I am sure MySpace would be more that happy to help authorities, all they are asking for is a piece of paper that will protect them. They are not deliberately defending offenders nor are they complicit in the actions of sex offenders. All of the headache would go away if the AG office would follow due process and provide MySpace (and any other company/service provider in a similar situation) with a valid subpoena then no-one can cry foul play.
Too many people view a subpoena as a document delivered to force an action, in a lot of situations like this it should be viewed a document with two purposes:
1) To protect any party from whom information is requested to facilitate in the tracking of and possible prosecution of anyone commiting criminal activity.
2) To ensure that any defense attourney cannot have any evidence gathered discounted by claiming it was gained illegally. Thus, giving an added possibility of a criminal escaping justice.