Knowing what homosexuality is =/= assuming the purpose of an innocuous-sounding phrase like "Interested in" is intended as a declaration of homosexuality, especially if you're living in an environment where you can't see why anyone would conceivably want to publicly declare it.
I suspect those least likely to select "interested in: men" are homosexually-inclined Iranians who know exactly what it's for and wish they lived in an environment where they could tick it.
you are insulting them saying they cant even understand plain english, you dont have to live in USA to understand what "interested in" mean in that context , there is nothing innocent sounding in that expresssion, and i'm not english nor have an english culture. Dont take aliens for fools.
I'll give you a relevant example:
Back in ~2006 it was possible to do similar searches within your college.
A disproportionately large number of people declaring their interest in both men and women were from China. Now it's possible that Chinese students were much more likely to be [openly] bisexual than British and European ones, but every shred of evidence I've ever seen (at college, in the media and living in a relatively-liberal ethnically Chinese country) points to the opposite.