Wow... interesting. I didn't think it was this common to disclose sexual orientation before gender.
Seems I'm the odd guy out!
I don't think cis people can ever really seperate sexual orientation and gender identity. I also suspect in the minds of many cis people - once you don't conform to the hetronomitive, you don't conform (and it doesn't matter how - all they think is "different").
I'm thinking they just react badly with the first disclosure out of shock-horror-probe that you don't conform. The later disclosure (ie, a change in how you don't conform) must seem a pretty moot point to them once they've dealt with your non-conformity.
Then again, if I knew what went on in people's heads - I'd write cleverly crafted slightly incomplete pop-psychology books under the pen name of Captain Obvious and make craploads of money. I'm currently broke - so this post is probably way off the mark

.