Remember that china is an isolated nation which means that no information could easily go in or out in the country.
Biological weapon has started since Sars, that is why the Covid is a strain version 2. Using their own people is an intelligent move to hide their true motives.
maybe I saw this articlehttps://www.nationalreview.com/news/border-patrol-stopped-a-chinese-biologist-carrying-viable-sars-mers-viruses-at-detroit-airport-in-2018/ and I was shocked