That's the point. It wasn't. There weren't any trans women mentioned or alluded to in the epitaph, and the person assumed to be was not "dehumanized". I'm honestly puzzled by this.
I would be much more sympathetic to the removal of the poem if it weren't over an obvious misunderstanding (or deliberate misreading) of it.
You are blatantly wrong. Sleeping with a woman, and later finding out that person is "actually a man" has been a common trope for the last 20 years that degrades trans-women (see Ace Ventura, Always Sunny, Jerry Springer, etc. I really don't think this is up for debate).
For you to think that this was an obvious misunderstanding, or some sort of internet conspiracy is insane. Please just stop.
It's a joke, one not really meant to paint anyone in a direct bad light, it's only degrading if you perceive it that way. If anything, it mocks the sexual insecurity of men or at the very least jokes about the awkward situation that, to this very day, sometimes happens between men and trans people.
I can however safely say that if you and others keep reacting to harmless jokes like this, you will ultimately just create further gaps between people, because what you're essentially asking for is special treatment. Trans people are not special, they are humans, capable of humour and being joked about just like any other group of people. Jokes are not a problem, stereotypes are not a problem.
You know what's a problem? People that seriously go "HAH, THIS IS JUST HOW x PEOPLE ALL ACT, THEY'RE DUMB AND SILLY", which honestly would be like that regardless if the joke or stereotype existed or not because their views and opinions were not created trough some silly joke but rather trough ignorance. Frown upon the people that do this, instead of the jokes and stereotypes, because any sane person know the difference between jokes/stereotypes and real life, just like with TV, books and games. You can tell me thousand of offensive jokes and it would change my mind about black people or any other group of people.
I would however laugh at most jokes probably because I love offensive jokes and think they are good for breaking barriers and also for pointing out just how stupid some stereotypes are.
I think this song sums up my thoughts on this.