I think it's that bathrooms are a place that are still gender-segregated, and where people feel vulnerable.

The patriarchy is a real thing that makes all of society asymmetrical among women and men, but focusing on the bathrooms is (1) simpler than all of that, and (2) something you can do without acknowledging the sexism built into society.

It's one place where you regularly make yourself vulnerable and to the mercy of the public, with a nice viewing-gap in every stall for some reason.

Say you have a red-blooded American idiot, feeling that natural vulnerability you feel with your cheeks on that seat. They sit down, and Tucker Carlson's visage appears in their mind, saying, "Be afraid! A transgender will RAPE you! It can HAPPEN RIGHT NOW!" And the transphobe wipes, get up, and get ready to leave, hands shaking ready to grab your pepper spray if there's a transgender on their way out.

But if you're just Any Transgender Person using the bathroom, it's probably the number one area where you can anticipate conflict. It was probably pretty scary the first few times you dared to use the "other" restroom. If you've been trans and using restroooms for awhile, you probably had conflict in the past.

You know now you got out safe, but those conflicts didn't start with that assurance. You wouldn't know if they would escalate to violence.

And when people feel increasingly empowered and even mandated to start conflicts at the bathroom, that die rolls again and again. Maybe next time you'll get shoved, or even pepper sprayed, or assaulted even worse.

So, the transgender person sits down on the seat in the adjacent stall, and the visage of Actual Conflicts You Had appear in your mind, saying, "Be afraid! Someone might yell at you! Or worse! It can HAPPEN RIGHT NOW!" It doesn't matter that the trans person has reason to be afraid and the transphobe doesn't-- both are afraid.

The trans person wipes, flushes, and goes to wash their hands. Your cortisol is up, and even just a scornful stare is enough to bring it higher.

I've definitely left situations like that feeling, "fuck!! i have all this anxious energy!! i need to POST about it", falling for the exact thing you described. And then Fox fucking News wins again.