No because looking like a turtle is not specific to their being “trans”.
Let’s use a truly transphobic example.
This picture takes a unique attribute to trans “Women” and makes it the butt of the joke.
You see the “Rotten crotches” are really depressing to trans “Women”.
It would be transphobic to make fun of the axe wound we call our vagina.
I think you are right. If I had known that cutting off my dick would leave me a depressed celebate slug of a human with the worst qualities of both man and woman maybe I wouldn’t have gone through with it. The spark of life God gave me has dwindled to a flicker of depressed truth that I will never truly be a woman.