It's a hoax only if it were intended to be perceived as something it wasn't. Evidently someone didn't bank on the fact that Americans are running scared.
I agree with you. I think it is going to be tough to prove that these devices were somehow planted with the intention that they be thought to be explosive devices of some sort. Who puts lights on bombs? I agree that these guys should have come forward at the first mention of potential terror connections, but I don't think this was intended as a hoax. As for the disorderly conduct charge, if this kind of act results in a conviction for that, the statute is too broad. Perhaps some sort of civil action would be possible, though.