Flying will be the place I always mask if nowhere else. Haven't we all gotten sick after a flight far more than any other activity over the years? Almost every bad cold or flu in the 10 years prior to this started 3 or so days after a flight. My one roundtrip in 22 was with a K-95 and no illness as a result. Also I can fall asleep and not feel stupid that I'm sitting there with my mouth agape in that awkward-plane-sleep position.
And the idea that any random group of 300 ppl, doesn't include at least one person with an active infection would be crazy these days. Of course, probably more than a handful.
One thing not noted in the article, is how closely the wastewater positivity correlates to someone who is currently infectious. IE, does your waste continue to shed covid a week later...two weeks later? etc.