This is honestly more than a bit presumptuous for you to say. Especially the "gun-to-your-head" analogy, as well as your rhetoric about so-called "genital preference"...

I have never felt remotely attracted to the opposite sex (women). And I don't need to "experiment" attempting to have sex with a woman in order to be confident in my identity. It wouldn't be fair to her, and it wouldn't be fair to myself.

Now, I do agree with you that it's likely there are tons of people out there who land at various points across the spectrum of bisexuality, and many of them would be reluctant to acknowledge it, due to heteronormative pressures. But that's for them to know and discover, along their own journeys. If they're in the bisexual closet, I wish they could become empowered to be true to themselves. Yet, who are we to impose that presumption upon them...when we don't live in their bodies or experience their hormones?

The mindset you are promoting is dangerously close to "omnisexism" (the premise that everyone is somehow inherently omnisexual, and that anyone who denies it is somehow lying to themselves).