The entire western MSM has become a huge propaganda machine against China in this US-China rivalry. Their reporting about China have almost always come with a heavy dose of projection, delusion or simply distortion, these include both FT and Bloomberg. I used to favor slightly FT over WSJ because its European/UK origin and angle, but not anymore. You can tell this not only from their reporting, but also from their readers' comments, which can serve as a window to look into the prevailing mood of these supposedly elites. That being said, they're still useful channels to understand the US/Western side of thinking and information. It's just that they're pretty clueless when it comes to the Chinese side.
As far as the US citizens or green card holders working in Chinese tech firms, let me just say that it'll take a while for the dust to settle and don't get misled by the initial reactions or precautionary actions. For the slightly longer term impact of these "US persons" ban, we can examine them in two primary dimensions: one is the stage and size of the company, the other is the importance and position of the "US persons" within the company.
As some members have already commented, in a big, more established and mature company such as YMTC, any individual employee, even at executive rank or critical technical position, ultimately has a rather limited impact. The FT report tries hard to portrait the situation as if Chinese tech companies are mostly critically staffed with "US persons." That is decidedly not the case, at least when it comes to companies like YMTC. In general, chip design companies or EDA companies turn to have more US-originated persons (either seas turtles or passport/green card holders), but fabs are more likely to have more Taiwanese or South Korean employees than "US persons." This was most likely to be the case when the companies just started, but would be diluted over time. So for YMTC, SMIC, or CXMT, the impact would be very manageable, particularly over longer term.
For tech startups, which include some chip design firms, EDA software companies and a few semiconductor equipment firms, the impact would be appreciably larger, due to the stage and size of the companies. Here, the second dimension kicks in, that is, the said "US persons'" role and position within the company. Firstly, chip design currently is not a bottleneck to the growth of Chinese semiconductor industry. China has very good, even world-class, indigenous chip design companies such as HiSilicon and ZTE's design subsidiary. EDA companies may be affected very differently, with the more established domestic ones minimally while the recent startups potentially affected to various degrees. There are a few equipment firms whose founders are US passport holders (I won't name names, but it's not hard to find out), but they have been established in China for quite some time now (>10 years) and have been quite successful. It's not difficult to imagine what choice they would make when being confronted with one.
In the end, it's a self-selection process: the more successful the companies are, the more critical you're to the companies and therefore the more stake you have in the companies, the less likely you would abandon it and the more likely both the company and you would eventually find a way out of this. It's people who are in the middle that would face a more difficult choice. But then again, it won't be a critical blow if they choose to leave.
Overall, when the dust settles and all is said and done, this "US persons" ban won't cripple the development and growth of Chinese semiconductor industry beyond the short-term. It just can't.