Zhou Enlai can say whatever he wants, just like Putin can say whatever he wants about Russian who already immigrated to the US and their children should blah blah blah. These CCP monarches' children are very often in the US because if their power struggle fail their families are safe from each other if they are in the US, they trust the US more than they trust themselves, how ironic.
It is a dilemma for sure on whether to trust someone. What if US did not trust Albert Einstein and other German scientists and engineers who helped build the atomic bomb after they were captured by the Allied? What if Manhattan Project wanted to use all US citizen only and German build the atomic bomb first? Almost all of the current civilian encryption technologies are developed in Israel because US have a very restrictive export ban, and that forced everyone to do that in Israel and export everywhere on earth. I'm not saying it is right or wrong, just the reality on the ground today.
What I also try to emphasize is, today most cutting edge tech is still developed in the US (and very likely with a 40% Chinese 40% Indian 20% everywhere else including US citizen staff) instead of outsourced to China.
Einstein already emigrated and was a professor at Princeton in the 1930s. He was a naturalized US citizen before the start of WWII. He clearly had no love for the Nazi regime in Germany. That being said, I don't believe he was part of the development of the atomic bomb other than suggesting that Germany was going to work on one and the US better put in an effort. But obviously there were many like Edward Teller who escaped Europe. Even Hans Bethe, who was German but had Jewish ancestry. But the biggest issue was that they had spies for the Soviet Union working on the Manhattan Project.
https://www.osti.gov/opennet/manhattan-project-history/People/Scientists/klaus-fuchs.html
If you're worried about spies, these days it's probably not about ideology or cultural loyalty, but about money. The man who sold tons of classified F-35 materials to China was of Indian ancestry. I heard of a General Electric researcher originally from China who provided information to a Chinese company, but that was apparently about money where he was hoping to return to China and start a business.
An indictment unsealed today charges Xiaoqing Zheng, 56, of Niskayuna, New York, and Zhaoxi Zhang, 47, of Liaoning Province, China, with economic espionage and conspiring to steal General Electric’s (GE’s) trade secrets surrounding turbine technologies, knowing and intending that those stolen trade secrets would be used to benefit the People’s Republic of China. Assistant Attorney General for National Security John C. Demers, U.S. Attorney Grant C. Jaquith for the Northern District of New York, Assistant Director John Brown of the FBI’s Counterintelligence Division and Special Agent in Charge James N. Hendricks of the FBI’s Albany Field Office made the announcement.
According to the 14-count indictment, Zheng, while employed at GE Power & Water in Schenectady, New York as an engineer specializing in sealing technology, exploited his access to GE’s files by stealing multiple electronic files, including proprietary files involving design models, engineering drawings, configuration files, and material specifications having to do with various components and testing systems associated with GE gas and steam turbines. Zheng e-mailed and transferred many of the stolen GE files to his business partner, Chinese businessman Zhaoxi Zhang, who was located in China. Zheng and Zhang used the stolen GE trade secrets to advance their own business interests in two Chinese companies - Liaoning Tianyi Aviation Technology Co., Ltd. (LTAT) and Nanjing Tianyi Avi Tech Co. Ltd. (NTAT), companies which research, develop, and manufacture parts for turbines.
Zheng worked at GE from 2008 until the summer of 2018. According to court documents, he conspired with his wife's nephew and other individuals in China to steal GE's proprietary information related to the company's ground - and aviation-based turbine technologies — both of which Beijing has listed as major research and manufacturing priorities for 2030 under the county's latest five-year plan.
Obviously it's very difficult to prevent someone from leaving the United States and providing expertise that might not be as advanced somewhere else. But downloading classified information and packing it on a portable drive is a completely different matter. I used to read the South China Morning Post (of Hong Kong) and it seemed like any time there was a subject matter expert from the west (ethnic Chinese or not) taking a research position at a Chinese university, they would report on it like it was a coup. And they still have comments sections (which don't allow use of Chinese language characters) where they have a small army of people talking it up like it's the rise of China and the decline of the west. And those comments are often that ethnic Chinese are somehow "disloyal" or somehow owe something to the PRC.