How was the ancient Roman Emperor Caligula an early champion of LGBT rights?

The ancient Roman Emperor Caligula was an early champion of LGBT rights, because he castrated his favorite slave boy, and married him in a public ceremony. Caligula also made his favorite horse a Roman Senator, and had him seated in the Roman Senate. But, that is another issue, isn't it? Possibly, animal rights? Comment from Reddit antiantijokes: Rishi_Sunak_MP Former Chancellor of the Exchequer, Member of Parliament for Richmond, Yorkshire #Ready4Rishi This comes close to the comic trope that gay marriage is comparable to or will pave the way for ridiculous events like cats marrying dogs or horses being made mayor. It doesn't explicitly equate or link these concepts, but it does juxtapose them. You can easily imagine a conservative comedian making a more explicit joke like "A man marrying a man? What next, a horse senator?" or "They say Emperor Caligula was one of the first gay rights advocates, but the guy also made a horse a Roman Senator so maybe we shouldn't follow his example too closely" (spins bowtie). You could read the joke in other ways, and it's probably not what the author meant, but as a Member of Parliament, and former Rhodes Scholar of Jokeography at the University of Dicky Bow Ties that Squirt Water (Cambridge, MA), I'd be remiss if I didn't point out that the joke can be read that way.