Because your post was very strongly worded and also broadly general. It was pretty much the same tone Chicup uses, just from the opposite perspective.
So extend it then. What if Chicup had said that all of the husbands he knows in the lifestyle have indicated that their wives don't have this fantasy? That would effectively be the same thing. Point is I don't accept the idea that women don't feel "safe" sharing this fantasy because of some kind of fear of backlash. People in this lifestyle are pretty open about sexuality.
As for a guy not being bi, yet being willing to have sex with another man to satisfy his wife, I find it incredibly unlikely.
What would we say to a totally straight woman having sex with another woman, despite having no attraction to women at all, just to satisfy her husband? We would say it was tragic. We would say she "took one for the team". We would say it was lousy, etc. We might even say it was abusive of the husband to push her, etc.
Now *could* that happen to a man? I suppose it could. Is it *far* less likely? Yes. I think the *vast* majority of the time, a man who satisfies this fantasy for his wife is by definition bi-curious and, if he in any way enjoys it, he is certainly bi-sexual in some way.