Straight is defined as a strict attraction to people of the other gender. It doesn't matter what history there is, or what culture changes around us. The core definition of straight is strictly incompatible with people who are attracted to those who are of the same gender they are.
I do get what you are saying, in some ways, but really I think it's less a matter of if these people are "straight" and more a matter of if "straight" and "gay" and "bi" are even functional or reasonable lines with which to group people.
Perhaps they were reasonable in a time where we needed a hammer, but now when we have power tools and all sorts of "social technology" our viewpoints and systems can be far more advanced and nuanced. "Straight" as a classification may be similar to "the element of earth" as a means to understand the composition of wood.
It may well be that "straight" and "gay" are less innate parts of our being and more akin to strong fetishes. That doesn't change what it means to be straight or gay, it just changes what place those phrases has on our views of ourselves and each other.
Regardless, if you are attracted to (having sex with) other men, you aren't straight. There is no way I'll ever accept any debate to the contrary because it just doesn't fit with the term as it is defined.