This was the second thing cis lgb individuals had a hard time understanding. Being out as trans is different to being out as a lesbian, say. Both can be dangerous, true, but they're not even remotely the same if you happen to be binarily gendered, like I am.
It's 'cos I don't feel particularly trans, and I'm not probably even remotely genderqueer in any way. My sexuality's queer, thank you very much, but my gender is woman, and my sex is female. There isn't anything special there. And being out about the history of my body is, frankly, a completely ridiculous thought. The only people who really need to know are the people I have sex with, if the said sex would involve something a trans body is not capable of, and a cis body is capable of, or if my personal history is really relevant to the things I'd be doing with my lover. It might, but it's my call - after all, I'm responsible for my life, health and all such, not anyone else.
And as to being queerly sexual? Well, it's not much good being out about that, either, 'cos I'm monogamous, and partnered with a woman, which means I'm effectively read as a lesbian, and it's not too wrong - I really do love women and all that lesbian stuff, and again - why should my queer sexuality concern other people so much 'cos I'm not gonna be doing it with them anyway? And if I am - let me tell you, I can open my mouth and say what I like.
But being out as a lesbian? I think I do that as a matter of course. The sex/gender of my partner's no secret, and the fact that we have a, erm, carnal relationship can't really be missed by anyone who's seen us together for more than a few hours. It's no big deal being out with that, 'cos it's something anyone can see - I don't have to go out of my way to explain it to anyone (ok, there are those odd people who just don't get it that two women kissing each other on the mouth is, like, homosexual, but they're beyond my help anyway) - they can just see all of it in action and that's that.
Whereas my trans past/trans body needs a whole encyclopedia of explaining that almost no-one really needs to know, and can't figure out on their own because it doesn't change things for them in any practical way unless they're having the transphobic cooties.
So. I think when well-meaning (or not) cis homosexual people want someone trans to be out about their cis/trans status, they're really wanting that trans person to be a miner's canary for transphobia. Of which the cis people themselves don't have to suffer any consequences. So it's kinda unfair, and I'm not playing along.
It's also about establishing and maintaining practical power differentials: it's about keeping us uppity trans women in our place: Lord forbid what'd happen if we were just taken to be regular people with control of our lives. If cis people aren't constantly reminded of my past they tend to slip into the realisation that I actually am a woman, which is kind of a tacit acknowledgement that all that sexing-at-birth went titsup anyway, and doesn't really work. Which destabilises cis sexes and genders quite a bit, because if sexing went wrong with me, what's stopping it from going wrong for everyone? It also puts the cis on equal footing with the trans, which might be a bit unsettling for the cis, too - no "other" to define yourself against.
Oh yeah, and if you're cis and don't like being called cis - tough titties. I didn't choose to be labelled as trans, either.