More and more, it seems like the "can't live as self" is the sticking point for why this is a genocide. "I am a woman, but I'm being forced to live as a man, which means I have been erased as a trans person and thus a trans person has died whether I physically still exist or not". While the dynamic is obviously MUCH different, Marrec is right in the sense this is identical on the surface to replacement theory, even if trans people undoubtedly ARE a marginalized group.
But hiding who you are, as much as it sucks, is not a new thing for many groups nor does it constitute genocide on its own. There are still parts of the country where you can't admit to being Jewish, but no sane person would say there's currently a Jewish genocide going on in America. Hell, I don't even think people were saying that about Muslims post-9/11 (correct me if I'm wrong) and there was some absolutely vile stuff being proposed both in government and by your nice old neighbor down the street, much worse than what's going on for Trans people now.
It's funny because I remember there was some point of contention between black and jewish people on a small "oppression olympics" level that jewish people were capable of "passing" and so they didn't have it as bad, an argument that made it into Spike Lee's BlacKkKlansman. Trans people have completely leap-frogged that argument and now non-trans people that are incapable of "passing" can't say anything because of how vicious the discourse has gotten.
The other thing that apparently constitutes this as a genocide is the lack of gender-affirming care. Again, this sucks, but genocide? Is there a genocide going on against depressed people too poor to afford a therapist/medication? Hell, you could extend this to everything medical or unobtainable basic human rights like food, but as much as this group wants free healthcare and the death of capitalism, I've never heard any of them refer to the lack of it as a genocide for the general populace. There have been no genocides in the past that were predicated on the idea of higher than neutral (food, clothing, shelter) human rights being denied. EDIT: Hell, even the ones that HAVE like the Great Leap Forward, people still argue whether they fit the definition of genocide or not (It was).
And I don't know if they realize how much the sports argument is a losing position without aggressive education on the issue that most people don't have or want to have, and the only reason it hasn't cost dems electorally is people frankly don't give a shit about women's sports, certainly not enough to offset the independent disgust over how much of a conspiracy-fueled dumpster fire the GOP has become.
Maybe they're right and this is all a prelude to something worse, and the separating kids thing is fucked if true (I haven't looked into it), but for now it just seems needlessly alarmist that will undoubtedly damage the cause.