GGL Beef posted that in error, which was corrected later. The Official Rules, on the other hand, clearly stated that only legal residents of the United States were eigible to enter the competition, which is why I said you should not have joined the competition in the first place. I apologize for any confusion from Beef's error, and he has apologized in the forums as well.
By no means does this mean you are not welcome to participate in other GGL competitions - there are often very different eligibility requirements for different competitions. It usually depends on whether we have an official parter for the competition and what that partner's requirements are. In this case Sony asked us to make it a U.S. only competition.
As to why we let in teams from other countries, it is because there is no good way for us to automatically block them. Items like country and age are unverified during registration, otherwise we would need to require a credit card or some other method that would make the registration process too slow and/or painful for many users. Instead, we require that our competition participants read the rules and agree to abide by them. In cases where someone raises a dispute or an admin notices something wong, we investigate, and we almost always require proof of those things at the point we give out prizing. However, in any online competition, you have to rely somewhat on people policing themselves and each other to make sure everyone is participating fairly.
So, again I apologize for Beef's erroneous forum post, and hope we ca make your future GGL experiences better than the Warhawk tournament was.
Thanks,
GGL Prize Team