This seems identical to saying that convincing someone with anorexia that they aren't overweight is "social death", and "social death" is (somehow) genocide.
To say nothing of using the same word as what happened in the holocaust or to the Armenians or native Americans or Rwanda or is happening in Xinjiang....
dysphoria is certainly a mental illness, transitioning is merely one possible treatment for it (though, pushed as one of the first rather than as one of the last options, which I personally find concerning.)
Being gay is not generally recognised as mental illness, although it has been in the past. Being trans is less well defined (historically even being gay was not well defined, or defined the same way).
I.e. it's nonsense.