question about an internet 'stalking' kind of a thing and legal crap

ok, a friend of mine who lives in the USA is a member of a message board for fans of a band in the UK.
the son of one of the band members also frequents that board... and posts. hes from the UK.

anywyas, he also has a myspace and my friend was playing around and posting crazy cat pics on his comments section and he kept deleting them, because they were annoying, and she posted one cat pic.. of a nuclear cat, lol.. and it read "Things go boom!" lol. it was just stupid and funny, no harm in it.

anyways, this prompted him to delete it and also take her off his friends list.

a couple weeks later she was playing around on the message board with a couple of us (i'm a regular, well was..), and most of the fans on that forum hate this other band we like and always bashing them, so we went on there defending it, and just being silly and posting crazy shit (ok, wwe were kinda spamming it with crazy cat pics and shit). nothing threatening or anything. just really lame, bullshit. and we all got banned.

so then my friend, started a little fan board on the kids dad, the bassist. it was to go along with these other fan sites of the band. it was nothing bad or anything bad said or defamatory.


anyways,.. some idiots over at the main forum, started fucking around with the other members' accounts, tryig to obtain passwords and stuff. and posting anonymous defamotory messages to US.. when we did NOT to them. and i mean bigtime defamatory stuff.


so we reported this to the webhost security dept. and they were looking into it... with the Ip's we had and all.

anwyays, one member looked up the one IP of one of the "hackers" who was also posting some nasty messages.
to which he lived in an area in or around the band member's kid. so, one of the forum members wewnt and PM'd him and asked if he was messing with the accounts etc etc.. band kid freaked out.. went to the moderatr of the main board, complaining and freaking out and then we sent an apology, it wasnt even the kid doing the hackign afterall anyway. we werent even going to accuse him, it was the other guy who went off and started flipping out at the kid. we didnt even know he did it till afterwards. so ths was going to start all kinds of crap. great.

anyways, we sent an apolgy to the kid and he wrote back to my friend that if he ever sees his name memtnioned on that board by any of us, or by anyone else, he was going to take this further than just a PM and i guess legally.

could he actually get a legal thing on this nonsense??? whats the worst that could happen>? theres absolutely no proof or anything that anything bad really een happened!