OK, I'm going to hate myself for engaging with Hang 10, particularly as his "point" has been addressed ad nauseum.
You seem to equate sexual assault with the presence of disparate genitals in a bathroom. This just does not make sense. Let's start with a point that has been made at least a dozen times in this thread. Unless your community is different than mine, you currently don't know the biological sex of the people in your public bathrooms. I don't think I've seen a set of genitalia in a public bathroom except when I've changed a baby. That's because peering at people's genitalia without consent is gross, icky, and a crime. It's all of those things whether the person doing the peering has the same genitalia as me or different genitalia than me.
As has been pointed out, the majority of transgender people are attracted to members of their birth sex. So if transgender people were advocating for using the bathrooms that offered them the best peeping opportunities they would logically want to be in the bathroom with the gender they are attracted to. Of course, transgender people, like everyone else, really want to go in the bathroom where they feel comfortable, but even assuming your ridiculous fears were warranted, you've got it completely backwards.