The time of day that these generally happen would lend credence to your thought -- perhaps a kid who posts his hit & run just before hopping the bus to school. In that event, his parents/parole officers would probably be very interested in this.
Also, as I said before, I'm sure this violates his ISPs Terms of Service.
If he can be tracked, I'm sure we can get his internet access revoked if nothing else.
That's about all that can be done. I'm not a lawyer but I'm 99.99999% sure that anything attempted legally would be laughed out of court.
So people need to stop fantasizing about legal action (unless they're going to lobby for new laws which is a whole 'nother can of worms) and talk about changes to FR (perhaps LONG probationary periods before posting pics is allowed, etc) which is the sort of thing I'm sure a judge would ask about before he giggled and threw out any lawsuit.
The last thing the legal system wants to get involved in is policing bulletin boards; they're going to ask what steps FR was doing themselves to restrict registration, etc.