My country deals with Rohingyas, the Burmeese have different views than what you think. The comparison is fine.
A clan is not a family. It is big. Even Orochi said that his grandfather being forced to commit seppuku was one thing, he accepted that. But people of Wano started delivering "justice" by killing women and children of Kurozumi clan.
If anything, it is the Kozuki clan that started the first mass death in Wano. Because Orochi didn’t even manage to exterminate Kozuki clan in the end. And he imprisoned other people.
Ok, not getting into real world politics.
I agree about the joke. It was bad. I'm just stating that from a storytelling point of view, any presented Kurozumi was shown to be evil and commit atrocities, regardless of how they got there.
Maybe there's more to this story. Maybe pictures show different context. Yamato is a Kurozumi from Kaido and a young Higurashi and it makes people think. Maybe that's something that Oda wants to touch on or will once backlash is received. Maybe dialogue is changed in translated versions or volumes edit out the dialogue with something more tasteful.
Or maybe it just sticks and that's it. Oh well, Wano is a shitty isolationist country then with clan issues. Don't know what else to say lol