This has come up before. Not tossing out infractions or anything here, but I do want to hand out an explanation.
Trap in that way is a slur we don't allow on SV. Yes, it's a slur, yes, it's been prohibited here for literally years now, and yes, it's even specifically used in the rules as an example. We've had Staff and regular posters have that screamed at them IRL as an insult and worse, so it's not just a fluffy anime term because it's used that way on some sites or boards.
I'm just going to reuse the words one of our directors used in a similar case a while ago: The term isn't a mystery. A lot of the trans people we have on SV are themselves otaku and familiar with the term, the character type it refers to and so on. It's not some mystery that they, or us for that matter, had never encountered before.
Moreover because we are familiar with the term we can say that the idea that it's not a bad term is somewhat naïve. Even setting aside that it's a gay panic joke where the gay panic has subsided somewhat, the character type itself - the otoko no ko - is very often used in pornography that sexualizes young boys or is pretty much rape. It's not all Juns and Totsukas. Moreover, it is not uncommon for transwomen to be treated like they're actually crossdressing men who catch men in insidious gay sex traps, so they're understandably sensitive about this. Considering the inherently negative connotation in the word 'trap', its origins as a gay panic joke, and the concerns of a significant portion of our userbase, we don't allow the word to be used.
So just an advisory, kids: Don't giggle and toss 'trap' around here.