Why are gay men threatened by straight men having sex with men?

There was a post at a website titled, "Queerty" http://www.queerty.com/read-this-if-you-wanna-learn-how-to-seduce-straight-guys-20111019/ which was called, "Read This If You Wanna Learn How To Seduce Straight Guys". Queerty.com saw an article I wrote on Psychology Today about straight men having sex with other men. What baffles me are the comments of gay men who are naive and ignorant to understanding that men can have sex with men and not be bisexual or gay. I would be interested in responses here from some of you as to what your thoughts are by the comments on that site. It is clear from reading this blog and the www.straightguise.com website that I do believe and know that bisexuality exists. I acknowledge that and talk about that when it is true for some men. One comment was that, "if a man is having sex with both genders than he is bisexual". This implies that bisexuality is simply based on a sexual act which would then have to mean that being gay and straight are only based on sexual acts. I always say that if I never have sex with another man again for the rest of my life I will still be gay and I know that to be true. Gay men who are hetererosexually married and having sex with their wives are not bisexual after they come out. They were always gay. Here is the website page and the comments http://www.queerty.com/read-this-if-you-wanna-learn-how-to-seduce-straight-guys-20111019/