Hmm. It probably depends on the bisexual person? Some bisexual people are definitely believers in binary gender. But I haven't surveyed what people mean by bisexual. That would be interesting.

I just personally find "pansexual" to be a really weird term that I'm not comfortable using, although I guess it might be more precise. "Multisexual" is worse.

I actually mostly use "queer" to describe myself as a way of getting around all of that. Instead of struggling to be precise, I will be vague! O_O