In this particular case, it's because JP is very much vocal about both of those things. He is a cisgender male who is only objecting to the suggestion of the existence of an alternative to being the gender you were assigned at birth.
English is a gendered language, therefore it's important to gender people for basic communication.
"Cis-male/trans-male" is more inclusive than the cisnormative "male/trans-male".
So until everyone accepts that "male" includes cis and trans, anyone who intends to respect basic human dignity will use "Cis-male/trans-male" when discussing gender. Simple as.