You're only being zealous about the fetish.
"Cuntboy" makes an implication that they were born a male but have a functional vagina and female reproductive organs, just as "futanari" implies they were born a female but with a functional penis, sometimes also a vagina. There's a difference between naturally growing into these forms, in fiction, as with cuntboys and futa, and undergoing surgery or therapy to reach these forms, as with FTM or MTF transgenders.
As a gay male, I don't have any interest in biological females, but I like vaginas. The thought of these characters being biologically female, BORN female, and undergoing therapy to be more masculine, makes me as uncomfortable as people like you might be over this term. Just leave it alone.