Free market does not need to be a two way thing to function. If the Chinese have to spend their money on non-US goods, those earning thw profits will be more inclined to spend their money on US goods.
Exports is what you pay for your imports. It's better for US citizens to be able to buy Chinese products even if Chinese citizens can't buy us products. They can pay for it by exporting to other countries from which China buys.
Meanwhile, when smaller countries (for example post communist ones) try to protect like that, all Americans were yelling "free market, free market, gotta open it completely and absolutely for the good of all!"
This situation should've been stopped a while ago, China banned every company they wanted while the others let them operate everywhere according to the free market rules.