As long as they have a license lol. It's up to them to take it to court. Someone here jacked out theme which we have had for 6+ years and when we persued it legally they just moved the site off shore. Xenforo did look into the matter but said they couldn't comment on any actions taken against the license if any.
Actually it appears that the "spoof" site is actually the real site with some sort of man in the middle hijacking in play. It's a 100% live result of everything going on in the real site. New content and data such as online users is always there. Logins work any any changes made are immediate. Its not a database copy. It's some sort of neat trick probably designed to steal information.