As far as I know the Chinese will prosecute their own citizens for making "seditious" posts even in foreign countries. But thats just because they have jurisdiction over their citizens, I mean America and Britian do the same thing not with speech but you can't go to another nation and have sex with someone under aged even if it is legal there. It's the same thing, where you go doesen't matter as long as you are a citizen of a nation there laws still bind you. If you are a popular foreign person who is known to be anti CCP they may deny you entry into the country, but well other nations also prevent people who are hostile to their nations from coming in. If you have evidence of the Chinese either kidnapping non Chinese to put them in jail, or arresting tourists for things they said outside of China then I would change my mind. But to me it seems like the Chinese are more interested in trade and bussiness with their vassals like with Africa. They don't seem to want to force their ideology on Africa or convert people like the west does with democracy.
Now I do think that we should honor our comitments and if China attacked Japan or Korea we should defend them, we need to keep our word. Also those nations are good trade partners and allies. However Taiwan we should make steps to pull away our guarantee of their defense for a few reasons. Now to the best of my knowledge if China attacked tomorrow we would have to defend, but our alliances don't have to last for eternity, we can seperate. There are places that are too close to our rivals that we should pull back from.
Do you think if they conquered Taiwan it would make it a powerful navy that could patrol the world's oceans? The way I see it China is the world's largest nation, their people are not inferior idiots presumably. They will catch up with us technologically eventually, this would have happened no matter what eventually unless we actually made China part of our nation, the window for that closed when we refused to use nukes durring the Korean war at the latest. The Chinese have historically not been a naval power. But if they see us as a rival they may decide it is needed and build up a long range navy to challenge us. And then it becomes a game of who can entice more nations to their side. Yes east Asia is on our side, but if China modernizes to our level they could pull nations in the middle east or South America to them since they never oppressed them, while we have towards south America and the Middle East.