Wouldn't that suggest that there is something wrong with the option to self-identify?
If one person says that it's a homosexual thing (or whatever) and then they share evidence, but that can be contradicted with "but some of the men who have sex with other men say they aren't homosexual", it makes it kind of a pointless diversion, since we would still consider them to generally be in the ball park of gay men.
I mean, if it's a "man on man" thing, then it's a "man on man" thing. The waters are simply being muddied with semantics and self-perception.