Yes this is for everyone including citizens. It's a response to Omicron.
I see official posts indicating that (1) layovers under 24 hours (2) delays in subsequent flights - do not affect the timeframe of the test taken within the required period prior to the original flight. You should have more faith in the US travel policy. The biggest issue, of course, is with the airline counters outside of the US where someone barely able to communicate in English have an absolute power to deny your boarding. US is not the problem here. I would still pass on traveling unless absolutely necessary, though.