I agree with you that nobody should enforce their standards (for sexual relations) on anybody else. But calling it a "choice" can be disingenuous.

Homosexual and bisexual attraction aren't "choices," at least not for everyone. Neither is cisgender attraction (again, at least not for everyone).

The core issue creating contentiousness here is how people who identify as pansexual or omnisexual are trying to shame cisgender people with the "How-do-you-know-you-won't-like-it-unless-you-try-it?" fallacy, while simultaneously trying to paint us as "transphobic" unless we defer to THEIR (pansexual/omnisexual) narrative.