I'm not sure what you expected when you started the conversation by comparing transexuality to otherkin. Upvoted so this post doesn't fall off viewability, but I think being confrontational about this sort of thing is taking the wrong message away. If you want to discuss a topic you have to be open to people with views that you may not agree with, and be able to see how they can come to those views.

When you talk about transexuality as a mental state, of COURSE it is comparable to other examples of mental states, and you have to be open to talking about it all if you want to be able to differentiate it.