Back to our originally scheduled topic...
Human sexuality is obviously more fluid for some people... and even life situations can alter sexual behavior (sex in prisons, being just one example). For those people who tend to see things in black and white terms (because of THEIR sexual proclivities), it seems harder to accept the grey areas others may inhabit. Any group each of us is not a part of is automatically suspect, even if we all don't feel the need to cast aspersions on others because of those differences. This not only impacts issues of sexual orientation, but also gender, race, ethnicity, religious affiliation, etc. It doesn't really matter if that's good or bad, it's human nature.
Compounding that, human sexual behavior is frontloaded with even more baggage because of a) societal expectations and b) the fact that it's really the ONLY behavior we exhibit that is most directly connected to who we are as individuals. Almost everything else we do in life is based on how we were raised or what we were taught at school or what we learned in church or how we interacted in social settings, etc. Sex, at least, initially, is something that is more instinctive and less an instructed behavior. Any attack or even criticism of who you are sexually (by a partner or by greater society) can cut deeply, because it's a fundamental reflection of who you are in a way that a learned behavior is not.
In terms of the initial post, even though it's 2006, I am sure there are still married men who probably lean to the homosexual end of the Kinsey scale, but who are not willing/able to accept the societal judgements that would go along with living out that option. I'm sure there are also married men who are primarily hetero-oriented, but maybe experiment a bit, and it's just as myopic for gay guys to call them "closeted". And I am also sure there are married men whose own sexuality is less restrictive and who have a greater capacity for deeper relationships with both women and men. I think our need to label each other is the problem that people bump into constantly when things seem to get muddled. As long as the parties involved are adults and honest, these are things only they can work out - or not.