Yes, on one level. Transphobes are hateful bigots who fear nonsense.
But (bear with me) it makes sense that some people spout nonsense about transfolks. Boundary crossings and category annhilation are just difficult for humans to deal with. And when we're anxious humans invent explanations, often absolute nonsense.
For example material from but no longer part of the body. Piss, shit and blood of course, but hair, nails, and even worn clothing are gross, dangerous, used in magic. Because self/non-self is a hard boundary we use and anything that problematizes that boundary is gauranteed to make some humans very uncomfortable.
Gender, likewise, is an ancient boundary. Most apes and many social mammals show gender based social roles, so we're talking millions of years. Gender has been central(ish) to human identity as far back as we can see.
Problematizing our artifical gender binary threatens those empowered by it (cis men), and challenges a category with deep roots. Many cultures often have third or fluid gender roles - people en masse can accept a more complete picture of human gender. But of course the process of change will make some people uniquely uncomfortable and thus spout nonsense.