I get the impression they've reused this AUP from a shared hosting environment though, as banning CGI scripts, "chat rooms", and background services are not things practical to police on VPSes anyway but are commonly policed on shared hosting. Statements like "Any database stored on Atlantic.Net servers shall be limited in size to 50% of the total disk space allotted for a particular domain" seem to back up this hunch, since it's talking about space for a "domain" and not a VPS or server.
I think they need to improve their AUP as I'm not convinced that it's what they intend for VPS services, too much of it doesn't make sense for that sort of environment.