Let's say a woman hypothetically was known as a lesbian prior to her transition, like publicly. Then she transitioned and now he is known as he but married to a woman still. That means that we would then be expected to perceive him as straight. This has nothing to do with social pressure against being openly gay/lesbian and is not gay erasure whereby those sexist people hating trans try to say it is wrong, with their heterornormative expectations that men cannot be feminine, and women cannot be masculine.