It's all about giving yourself to you OH. This is something most men never do. It's not about anal sex and it's connection to gay sex. It's about trying something different. Being the receiver or a change. The role reversal thing is a very strong desire in a lot of men but it doesn't mean that they are either bisexual or gay.
Unfortunately thats the stigma of straight men liking anal, me and the OH have done pegging for years! We have a best friend who knows more or less everything we do, only the other day I told her I liked bottom action too, she didn't know if I was jesting or not and her instant reply was "GAY BOY", had to explain that it's perfectly normal and that my OH has a strap-on and I have my own butt plugs! She was shocked and really didn't know what to say! Her attitude surprised me as we are quite open with everything else we do and some of that is quite extreme! Think outside of our world it's just not understood!
My OH often pegs me, would I ever consider myself gay.. no. Men don't interest me at all. But the power swap is such a turn on and yes massive orgasms from her pegging me is a bonus!