Zuckerberg himself said in his 2019 speech that they don't operate in China because "we could never come to agreement on what it would take for us to operate there." American tech companies absolutely can operate in China if they agree to abide by local censorship rules (like Bing is doing for China, like Google was going to do with Dragonfly, or like YouTube is doing for India). Facebook also has a substantial ad business in China [1]
> And insist that western companies give joint ownership of subsidiaries doing business in China to a Chinese company.
According to the Department of Commerce (https://www.export.gov/apex/article2?id=China-Establishing-a...),
> A large majority of new foreign investments in China are WFOEs [wholly foreign owned enterprises], rather than JVs. As Chinese legal entities, WFOEs experience greater independence than ROs, are allowed exclusive control over carrying out business activities while abiding by Chinese law and are granted intellectual and technological rights.
Also (https://arc-group.com/china-company-setup/):
> WFOE refers to a limited liability company that is 100% invested, owned by foreign investors, and independently operated. Almost 60% of foreign-owned companies are WFOEs, making it the most adopted business type. Famous multinational companies such as Apple, Amazon, Oracle, and General Electric are all examples of WFOEs.
[1] > Facebook sells more than $5 billion a year worth of ad space to Chinese businesses and government agencies looking to promote their messages abroad, analysts estimate. That makes China Facebook's biggest country for revenue after the United States, which delivered $24.1 billion in advertising sales in 2018 (https://www.cnbc.com/amp/2020/01/07/facebook-makes-a-new-ad-...)