They don’t seem to understand that genocide, as a term, does not exclusively mean a violent purge nor Holocaust. The erasure of a group of people can happen with minimal violence too.
It’s hardly surprising though, considering the USSR regularly practiced genocide with “Russification”. This wasn’t so much the violent kind, but more trying to erase a people’s culture and make them assimilate into Russia’s.
To tankies, that’s not genocide, even though it is erasing a culture to impose your own.