Furthermore, if someone said smth rude to me, I'd be happy to see someone else stand up for me, so yeah, NTA.

My experience living overseas in East Asia, and dealing with foreigners in America, including living with one for over two decade, strongly suggests that making a scene is highly uncomfortable. I’ll grant though that there are a lot of Chinese cultures and we don’t know what hers is. At least it wasn’t out in public.

My experience also suggests when living in another culture we do appreciate learning how to avoid accidentally offending people. However it is true that she was just eating and it wasn’t the best time. That’s why I was a bit wishy washy on whether he was an AH too.

Also where does it say roommate was mortified?

I expect OP was too busy bathing in her self-congratulations to notice.