I think HubPages, itself, has made it clear that non-Americans are more than welcomed on this site, but I think it's also clear throughout the community and in the interactions among the very diverse mix of people on here. Whether or not someone is capable of using English grammar in his Hubs is the one issue that people generally make when it comes to whether someone's meet "standards" (but a lot of English-speaking people don't use grammar very well either, so that isn't only reserved for non-Americans).
(I don't imagine I'm the only one on this site who has sometimes very much felt as if Americans on the site are in the minority. I love that people from all over the world can be on here, sharing ideas/discussions. That's the best thing about the Internet (as long as it's not the kind of sleazy, questionable, stuff that comes from US people, too, but that often comes from some countries more than others).
Personally, I'm not interested in the religious beliefs of anyone, no matter who they are. I don't have a problem, though, with someone from another country writing about something like, for example, the Catholic Church scandal. That kind of thing isn't an American thing. It's a "human" thing and in this example, a Catholic Church thing.
With politics, I think everyone (including Americans) should be extremely careful about being a) extremely well informed, and b) a reasonable and objective enough thinker before spouting off about politics in public. I don't see why anyone from somewhere else shouldn't write about it.
On some issues, people will, though, be at some disadvantage by not actually "personally experiencing some political issues". Regardless of where someone's from (including the US), I think people can't always have "legitimate" opinions about the kind of incidents/issues that require "up-close-and-personal" to be fully understood. Opinions about the "larger-scale-picture type of things are a different matter; and, personally, I like to see what non-Americans have to say about some of the larger-scale things too. I don't want to be exposed only to what is thought within our borders.
The one thing that does irk me is people who obviously hate America and/or seem to be anxiously awaiting some major downfall, who have little use for it or for Americans (sometimes only because of a preconceived idea about what "all Americans" are or do) but who come to a site like this to try to earn American dollars from an American site.