No one ever said it could! The article the medium post complains about called it a "content warning" not a "trigger warning". The "trigger" terminology was used

No one ever said it could! The article the medium post complains about called it a "content warning" not a "trigger warning". The "trigger" terminology was used by the medium post's author, setting up a bit of a straw man. However GP was arguing that any use of "trigger" outside of military trauma is appropriation, which is what your parent was arguing against.