Apple is required to follow the laws of the region in which their product is used so both of those scenarios aren't Apple "caving" to China. Apple is just following what they have to do for their software in those cases. In this case, it's someone else's software and they chose not to "cave" because there's no obligation on their part to take action since the app doesn't break any rules or laws.
Because it has, occasionally, in the past.
Apple doesn't have a perfect record when it comes to China. It's OK. I'm not sure I'd call it "good."
But between the Taiwan flag emoji, and the Chinese iCloud fiasco, my esteem for Apple is at an all-time low.