Not Saelune, but they seemed to refuse to accept it because they saw any negative representative of transsexuals to just be an attack on themselves.
If I remember, you're referring to a discussion about right wing youtuber Blair White, who made videos calling out Yaniv. These videos were brought up as a defence of Blair White's character in response to criticism of her politics. The implication was that, whatever those politics, Blair White was ultimately doing a good thing by exposing a horrible paedophile.
Saelune and I argued that, in the context of Blair white's openly transphobic views and habit of singling out and targeting trans people online, it was very obvious that her interest in Yaniv was entirely due to the fact Yaniv was trans, and to vindicate the preexisting belief of her audience that trans people are all dangerous perverts. We also pointed out the clearly political framing, despite the fact that White and Yaniv seemed to share a great deal in common politically.
The irony of accusing Saelune of not being able to handle "negative representatives" of trans people is that Blair White is trans. We were literally calling out an awful, toxic (and, yes, deeply deeply racist) example of a trans person in that thread, and your takeaway from that is that Saelune can't handle any criticism of trans people..
What the fuck.
My issue is with the specific details of them not actually being the sex they say they are because science has still not reached the point where we can actually change someone into a man or woman, we can only make them look like a man or woman and apply various drugs and hormones to influence their body, but their internal organs are still not changed.
A word of advice.
If you have not received any kind of scientific or medical education in this field, and if you are not familiar with the rudimentary basics of what the scientific consensus actually is and, crucially, if you don't understand what words like sex mean, you should probably keep quiet rather than saying stuff like this.
Morphological sex, which is the thing we colloquially call sex, is produced entirely by sex hormones. Using sex hormones and surgery to change the physical appearance of the body is already changing someone's sex. It's not perfect by any means, but sex determination is an imperfect process to begin with.
It is these internal organs and these unchangeable aspects that make me feel the previous law is not defined well enough because a doctor may need to treat a trans person as a male because various aspects of their body that are still male even after going through transitioning and someone calling that discrimination.
The same law prohibits discrimination on the basis of sex, and yet doctors have no issues refusing to prescribe birth control pills to cis men.
The vast majority of transgender people have experienced discrimination at the hands of healthcare providers, such as being deliberately misgendered or misnamed. One in five have been denied care at some point, including lifesaving care, because a medical professional refuses to treat them. If you want to see how bad it can get, look up how Tyra Hunter died and remember that no individual was even disciplined for that. That's why gender identity was added to the list of protected categories, because there is a demonstrable and urgent need for protections for trans people seeking to access essential public services.
I don't think it's relevant that you don't know what gender identity is, or how the law defines discrimination. That's kind of your problem.