Comparing furries/otherkin etc. with transsexualism is normally something you will hear as an attack from people that do not accept transsexualism.

I've heard the argument from both sides, including from otherkin who seek social acceptance based on that comparison.

I personally have no doubt the society has to accept and help transsexuals, but I'm ambivalent in case of otherkin - primarily because I find it difficult to empathize with their patterns of thought.