I believe the question is poorly phrased.
I think the OP is bringing up the issue of those cuckolds who are normally attracted to females, i.e., their own wives, and out in the world, they give nary a thought to other men in any sexual way. However, during cuckold play, these "heterosexual" guys enjoy the humiliation of eating cream-pies, sucking bull dick, and being fucked up the ass by bulls. For them, it's all about the power exchange as taken by their wives, and further intensified by being fully used and abused by the bulls. Their distinguishing claim is that, because they themselves do not experience an erection from any of these bisexual and homosexual acts, and because, outside of the bedroom, they are never attracted to other men, that they are still straight.
It's a complex question. But despite whatever psychological nuances, it is my contention that any willing participation in a homosexual sex act lands you in the homosexual category. Add whatever asterisks you like. That's my call.
A duck that quacks and swims far less than the other ducks, is still a duck.