The Mail Online is constantly dissed in left-leaning forums like this one, but if you just go read the articles and check the claims they're not usually any less accurate than any other news source (this doesn't mean they're very accurate of course, just that other sources are no better).
This article consists of some publicly known facts, along with some anonymous sources in the British government's emergency committee (the Cabinet leaks like a sieve so this is entirely plausible). It also cites an academic, some report from Beijing News (whilst noting that the report was retracted) and an academic paper that was uploaded and then deleted. It's written in a pretty neutral tone and explicitly calls out cases where its sources may have issues. The article is no different to the sort of speculation routinely found in Bloomberg, the WSJ, NYT, the Guardian etc.
What we're seeing here is just another day in no-platforming land. To the left what is said doesn't matter, who says it is everything. Based on prior experience I'd be willing to bet that virtually none of the people spitting fire over a Daily Mail or National Review link here have even read the articles, let alone rigorously apply the same purported standards to every news link they see posted.