As far as I know, once you turn something like this over to the FBI or other authorities, it's out of your control. You've already lit the fuse -- where the rocket goes from there isn't your choice.
Hypothetically, could Facebook later say, "Oh, actually, we're retroactively granting him access to our systems, so he didn't actually access beyond his authorization"? Or would that get someone at Facebook charged with making a false report to the authorities?
