> Off-Topic: Most stories about politics, or crime, or sports, unless they're evidence of some interesting new phenomenon. [...] If they'd cover it on TV news, it's probably off-topic. https://news.ycombinator.com/newsguidelines.html
Trump saying him and Melania testing positive for the Coronavirus four weeks out from the presidential election is huge news. This story is not about politics (i.e. about a political issue), it is about a political/world leader and his wife. Edit: So "TV news" covering the newest iPhone release would probably be off-topic too then based on this reasoning, but this seems to reliably hit the front page of HN everytime…
Consider that HN is all about intellectual curiosity. Imagine that the hostname is intellectualcuriosity.ycombinator.com rather than news. Debating product design is more likely to yield interesting thoughts/comments and much less likely to lead to a useless flame war.
The newsworthiness of a submission - which is huge in this case, as you noted - is a relatively minor factor for whether something is a good fit.