Foreign actor playing American--why?

Visually, this film is really creepy, even though there are lots of continuity errors, script problems, bad acting, etc. My main gripe about it, though, is their casting of a foreign actor (Nathan Spiteri as "Andy") to play an American with a terrible American accent (i.e., "my gehlfriend"), when there's nothing inherent in the script requiring him to be American. The character went to film school with "Mark," we assume in the States, but that doesn't mean he has to be American--plenty of people study abroad. If your actor can't do the accent, either get another actor, get a dialect coach, or rewrite the character. Don't guarantee your actor will fail by giving him a character he can't handle.