Even ethnic Chinese from Taiwan have been known to spy for Communist China (like the Chinese American who stole the plans for the latest U.S. nuclear warheads at Lawrence Livermore and is now teaching at a university in China).
The Chinese have a strong group identity and their nationality doesn't matter a great deal to them. In their mind they're Chinese, no matter where they live.
Harvard professor Charles Lieber had similar allegations, and he's not ethnically Chinese. There's millions of ethnic Chinese in Taiwan, Malaysia and elsewhere who are against Communist China. I agree the CCP has a strong 'ethnonationalist' ideology that tries to go beyond nationality. This needs to be strongly pushed back upon, but banning all ethnic Chinese is not the answer. Please keep in mind the centuries of historical context with anti-Asian immigration sentiment ("Yellow Peril"). I agree given the risks the world should put great thought into limiting (even banning) all immigration from the PRC because the security risks are too great. But that law should not apply to Taiwan, Malaysia etc if the people immigrating have proven themselves anti-CCP.
My motto is "better safe than sorry" as far as China is concerned. This banning doesn't need to occur at every company, only at the ones which are strategically important, such as defense and cutting-edge high-tech.
Don't give up America's values for even more state sponsored discrimination based on ethnicity. It does mean PRC nationals and others continue to steal, but that's something to be managed through the legal system.
The Chinese have a strong group identity and their nationality doesn't matter a great deal to them. In their mind they're Chinese, no matter where they live.