Because that would result in a more devastating response from the side that holds patents. If china stops respecting international trade laws and agreements, other nations will hurt china's interests in return. Given the scale of the things, the weak spots will be found inevitably.
There is a difference. Nobody in the first world really cares about Uighurs or Hong Kong. However, there are quite a handful of parties who do care about patents (and resulting profits).
China has been pilfering intellectual property from labs & private companies via APTs for the last couple of years: what are the handful of parties who care about patents going to do - write a strongly worded letter? If China decides it wants to get the latest ARM design and/or ISA in the future, do you doubt they can acquire them? Sure, they won't be able to call it "ARM" but you can bet it will be compatible[1].
For internal market, no, but they will have problems selling the pirate copies to the rest of the world. Most rich states do respect intellectual property.
