As a teacher and a sister with one gay brother and one straight brother, this question makes me think of many discussions with both brothers. In my opinion, gay people are like any other group in that some would be offended and others would find the commercial funny. I don't think that very many would find it a threat to their gender or sexuality. In my limited experience, being gay is not a choice; a Doritos commercial really has nothing to do with gender or "choosing a sexuality." As a result, I can't see this being a threat but maybe a tiresome stereotype to gay people,
As for being offended, that is another story. Many will find it offensive, as I do, because of the stereotype of the limp handed, flagrant gay man. I know several gay men who don't fit any stereotyped image. I get tired of stereotypes of any kind because they lock people into boxes from which they are not allowed to escape. My guess is that many gay people would feel the same way because of the stereotype used in this commercial. Some may find it funny, but my take is that it simply adds to the prejudice against anyone who is out and gay.