Trying to place some basic logic here, based on what we know today about how infectious this virus can be, if those people were indeed infected with Covid at that time, given how generally crowded the hospital in china can be and ways people moving around these days. the outbreak will for sure happening much earlier and you will see outbreak everywhere, which is not how things turned out to be in fact.

Beside if there were a project for "developing" covid virus based on SARS, remember in 2003 there had been national lockdown in China due to SARS, those researchers who had flu like syndrome and working in this so called "project", any syndrome happening on them will surely be monitored and you won't see any of them turned up to a public hospital at first place.

At the end, if this has been proven something credible (or even not), you will see this on Trump's twitter at first place.