"If you are massively only attracted to certain chromosomes, surely you just say that early on?"
People are same sex attracted, different sex attracted, or both. I'm pretty sure that nearly everyone is upfront about bring straight, lesbian, gay or bi. The mention of chromosomes isn't needed.
Occassionalnamechanger's post aligns with the TRA strategy of refusing to create or use new terminology. Different terms are needed to refer to people who are attracted to gender rather than sex, so those open to dating TW and TM can signpost this, and TW and TM can seek them out.
There are limited numbers of people who want to date, have sex with, or have relationships ships with TW and TM. This is a difficult and sad issue for trans people to manage. However, trying to dupe people into dating, sex and relationships isn't an acceptable way of navigating this.