That's not exactly true. While China doesn't detain US citizens (yet!) it detains several Canadian citizens presumable because the Huawei's CFO has been arrested in Canada by a US request. See https://time.com/5626289/china-canada-arrest-yantai/
Which makes things even worse - you may become a hostage due to US/China conflicts even if you happened to be a citizen of a US ally.
> We interred Japanese after Japan commuted one of the largest terror attacks in US history, that’s it.
1.) "We" did not inter Japanese. Those who made the rules and followed them during that time did. If by "We" you mean "Americans" then that leads to the next point...
2.) Many of the "Japanese" you say were interred were Americans. They were put into camps not because of any actual reason than how they look and where their ancestry hailed from.
3.) Imprisoning people who have done nothing wrong and have lived their lives in this country should make painfully clear the quote, "Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety."
As an American I'd think very carefully about working in China right now for the same reason. No matter where you are in the world, you're always breaking some law, and they can pick you up and throw the book at you to make a PR point whenever they please. Same as for a Chinese person in the US.
Feel bad, because the guys travelling to work or study really do just want to meet each other and have interesting idea exchanges, maybe make some friends, etc.
But then the political type people get involved, and it just gets a bit too complicated and you start weighing the potential risks differently.