a fictional character is not a real person.

Yes, but they can and do routinely REPRESENT a real person, or at least a highly-likely person.

if a writer intentionally makes a character gender-queer in order to emphasize that they’re scary and mentally unstable, that’s bigotry

Not only do we have zero evidence for that here, but that's not how Hollywood works, anyway. In reality, the pass-off from book-writer to studio to screenwriter to producers to director to actors is a multi-step process in which characters are commonly distorted from their original versions in to something completely different.

specifically about a character specifically designed to represent fucked-up-ness by having trans attributes added to them.

That's just your personal take, though. "First we create a fucked character, then we attach some trans attributes." You imagine it happening in that specific order, but I'd argue just as much that "BB" is a pastiche of dark characters that Thomas Harris found interesting in his research. BB could have been formed out of any combination of traits and known people, really, but it sounds like you're saying as a personally trans person (correct?) that you object to the fact that one of those traits seems to trans-ish? The reality is that any combination whatsoever is liable to upset someone who shares a commonality. And that's just the reality of life, like it or not.

I've watched the film like 2-3x over the years and never got the sense that they tried to lean too hard in to the trans angles (assuming they're really there in the first place) or tried to paint an overall picture about trans people in general. I guess it's understandable in our F'd-up society that you would be sensitive to that, so I guess I can understand your reaction. And credit to Levine's statement, which I do appreciate. I don't fully agree, but I like the idea of sticking up for trans rights.

I’m starting to doubt your participation is in good faith here.

Sorry you feel that way, Sarah. I feel that all people should be accepted for being who they are, as long as they participate in civilisation benignly. Something along those lines, anyway. With respect to nature and sustainability, of course.

The bullshit of Western Religion and power structures has done a number on all of us of course, including when it comes to the topic of "gender." So-called "conservatives" and power-structures always hate the idea of gender being a spectrum, for some pretty obvious reasons.