I don't think you need to exclude homosexuals. As a straight male, I interact with my homosexual buddies the same way I interact with my straight buddies. Women, gay or straight, interact differently, including those in whom I have no sexual interest.
If there was inappropriate behavior which wouldn't stop once called out, they would be excluded.
You specifically maybe don't, but homosexual (or bisexual) males do have sexual interest in other homo- or bisexual men. So it wouldn't be a "problem" as long as there exactly only one homosexual, or as long as they're a very small minority.
