I'm missing most of the context too, but from the twitter thread linked to by the dev, it seems that a lot of Chinese posters immediately started firing back as though he was attacking China specifically.
I know the Notepad++ dev has made some spicy comments but I don't recall if there were any directed towards the Chinese government.
It was related to Hong Kong and the genocide, which some in China agree with
I think it's similar to how certain Americans get squirrelly when people talk about racial brutality, like I imagine we'd get a lot of weird people sending cringe messages if they named a release "Justice for Trayvon Martin"
The creator titled one of the previous releases "Free Uyghur", IIRC, which made many Chinese users upset.
If you get upset by people who state that genocide is bad, you're rooting for the bad guys.
And a lot of Chinese do really think like that. They think the advancement of economic is more important than the freedom of ethic group (and their own freedom).
I'm sure even the most militant of CCP members would agree that genocide is not a key factor in China's economic growth.