>1) they can and 2) they do
For breaking PRC laws, not epidemic prevention. At end of day, countries wanted to repatriate and PRC obliged. It's asinine to suggest PRC can with hold foreign nationals, as if that won't spark a completely different kind of outrage. Obviously said criminals who broke PRC laws weren't repatriated. TW citizens from Wuhan was repatriated via rail to Shanghai. TW CDC had up to date release of repatriation flights and positives. Up till Aprial, TW repatraitaed about ~1000 out of Wuhan with 1 testing positive on an early Feburary flight. That's it. Because Hubei lock down was that effective.
> good approach to controlling the virus
Covid-0 strategy is probably the right one for PRC. More importantly it demonstrates containing covid was absolutely a viable. But other relatively milder intervention stratgies also possible as seen in other successful countries that adhered to basic WHO guidelines who didn't resort to PRC tier interventions. They were just slightly less successful. Even TW response barely ranks well when measured against other PRC provinces. Taking pandemic response seriously is correlated to serious results should not be shocking.
> was a valid theory
About as valid as Fort Detrick at the time (and now). Point is early lab leak propaganda was just that, propaganda designed to policized for Sino-US rivalry when origin tracing hasn't even begun and hampered subsequent efforts. PRC position has always been to let science handle origin tracing which in terms of propaganda is tame. Reality apart from delays around two-sessions in Jan PRC has provided more than enough info and signals for most serious actors to contain covid19 depite virus already spreading abroad prior to two-sessions or detection of market cluster. Or that there's still zero indication covid19 originated in PRC vs PRC discovering first cluster. Lot's of valid theories out there, but what gets pushed by whom and when and for what purpose is how things get politicized and what treaty is designed to mitigate.
At the end of the day CCP + WHO did fine, because those that took them seriously (like actually seriously) did Ok. Those that didn't, burned and have been looking for escape goats to their own failure.