I know nothing about the writer and the venue in which his comments appear. Also, I’m not qualified to evaluate the quality of his argument. Still, I find the hypothesis intriguing: Covid-19 is “being spread in the medical environment — specifically, in the hospitals — not, in the main, on the beach or in the bar.”
Hygiene failures, especially insufficient hand washing, would certainly explain why nursing homes have been persistent, readily identifiable hot spots for coronavirus transmission.
The main technical question I have about the hypothesis concerns the concept of “step funtions” in the statement: “The presence of step functions and apparent linear-fit line segments in what should be a clean parabolic curve says this is exactly what has happened.” I have only the haziest notion of what the writer is trying to say.
More generally, if medical settings are indeed a primary vector for coronavirus transmission, I can easily see why alternative transmission models would gain higher attention.