If it was an actualy HACK then he would have posted his webpage in place of theirs...ie...actually hacking into their webserver and changing out files.
Now THAT is illegal. Posting a website that is slanderous to another website is much less illegal. They could go after him but its a pretty weak case...
I've seen many a website come down at the hand of an excellent hacker. Sometimes they smash companies like these and completely change their website information to suit their own needs.
I guess if you piss of the wrong people and they have friends in the right places...you could be in trouble.
You don't hear many negative comments about shopforum...wonder why that is
Maybe 'cause Phil actually tries!