I would imagine China needs to sell them more than the US needs to buy them.
When you offshore production of a product, you rely on another country for a product. When you are the the country being offshored to, then you rely on that product being bought in order to generate income.
They might still be exporting them, but they obviously won't be exporting them in anywhere near the same numbers, which means a much lower income. This is all while the current tariffs are still affecting them. And we haven't even seen how Trump will respond.
Obviously, for most things, the US can likely find another source, whilst China cannot find a buyer to replace the US.
It's all really a question of how long the Chinese can afford to hold out.