Ah, I see. This is a common blind spot with respect to genocide. The word gets tied to the Holocaust and the massacres of Cortez, that it gives people an out when confronted by acts and attitudes that are very much genocide, but which do joy generate literal mounds of dead bodies.
And it doesn't change the dynamic with respect to service or product usage, because I can all but promise you that spez, and basically the entire staff of Reddit deny the ongoing genocide of indigenous peoples in North and South America, the ongoing genocide of the Roma in Europe, and perhaos - even probably - the historical genocides of these groups (with the possible exception of the Aztec).
I don't mean to come off as if I'm playing with whataboutism. I'm not. Genocides done here do not excuse genocides perpetrated by foreign cultures or regimes. It's just that if we apply the same standards to people who deny genocides being perpetrated by our own peoples and institutions, then we basically can't go anywhere or do anything ever. The only difference with that particular Lemmy dev is that they're playing rhetorical games about a genocide that most of us probably never would have heard of if not for the US playing politics with China.