Exactly who do you think is going to stop them? The citizens of Western nations may sympathize with Taiwan, but that's very different from them being willing to send their sons and daughters to fight and die for someone else's country.
If China decides to invade Taiwan, I don't see anyone realistically trying to stop them militarily. I imagine a bunch of nations will "strongly condemn" their actions, but I would be shocked if the West is even willing to impose economic sanctions in that scenario.
They invaded Tibet and East Turkistan. Those people suffer from Han-Chinese oppression.
Like with Russia, if the rest of the world doesn't draw a line, these horrible regimes start looking for the next victim.