Before you were saying 70% oxygenation is fine

I never said that.

I said that 70% wasn't necessarily a medical emergency requiring immediate intubation, and unlike you who makes assertion after assertion but rarely provides any evidence for anything, I can back it up including with a peer-reviewed case study of a Covid patient who presented with SpO2 of 70% and was then put on an oxygen mask, at which point she quickly went up to 85% or so, where she remained for 30 days before making a full recovery. No intubation required.

Plus the various other sources I have provided that pretty much say the same thing: stop intubating Covid patients just because they have hypoxia. There may be good clinical reasons to intubate Covid patients under some circumstances, but 80% or 70% SpO2 alone is not a good reason.

People can and do frequently tolerate levels as low as 70 or 80% for significant periods of time, sometimes without any distress, and even as low as 50% for short periods of time without suffering serious organ failure. You seem to be fixated on this idea that any deviation from normal range of SpO2 is a medical emergency causing organ failure and requiring immediate intubation but you are unable to back it up and unwilling or incapable of reconsidering your position in the face of evidence.

and there wasn't any obvious need to intervene in terms of benefit to the patient.

And I absolutely never said that or anything like that.

As I have said over and over and over again, non-invasive ventilation can and should be used before dangerous invasive mechanical ventilation (intubation). I don't know how many more times I need to say it before you will comprehend.

I said that hospitals should have kept the pre-Covid protocols, which had been tried and tested over many years. This includes the protocols developed for dealing with SARS. Non-invasive ventilation and prone positioning first, only if they do not help should you consider intubation, in which case you need to keep the sedation mild, and the oxygen volume and pressure low. I've said this over and over again, yet somehow you are still arguing against the strawman "don't treat Covid patients at all if they present with hypoxia until they go into cardiac arrest from lack of oxygen".

Either your reading comprehension is terrible, or you are arguing in bad faith.

... Or that intubation of a patient with "happy hypoxia" was done primarily for the avoidance of risk to the staff

I quoted the Wall Street Journal, and Theodore Iwashyna, critical-care physician at University of Michigan and Department of Veterans Affairs hospitals in Ann Arbor, who explicitly said that. Quote:

“We were intubating sick patients very early. Not for the patients’ benefit, but in order to control the epidemic”. (Emphasis added.) The article also says "doctors often preemptively put patients on ventilators or gave powerful sedatives largely abandoned in recent years. The aim was to save the seriously ill and protect hospital staff from Covid-19." (Emphasis added.)

Of course they were trying to save the sick as well. As I have said before, we should put aside overly emotional claims of "murder" by some front-line staff. (Although the evidence of involuntary euthanasia in some cases is undeniable, and some very suspicious patterns of use of morphine and midazolam in nursing homes.) I have never suggested that preventing infection of the staff was the only motive. But the difference between the pre-Covid and early Covid medical response:

• pre-Covid: use high-flow nasal oxygen (HFNO) or non-invasive ventilation (NIV), and only consider intubation if that fails to help;
• early Covid response: use intubation preemptively, avoiding the use of HFNO and NIV;

was driven by fear that HFNO and NIV would spread Covid to staff. That fear was ill-founded, and driven by an exaggerated sense of Covid's fatality rate, and the very real shortages of PPE in New York hospitals (remember the nurses using garbage bags as make-shift PPE?). Nevertheless it was a real fear and in fairness we should recognise that in the very early months there was significant panic involving Covid.

I'm asking why they didn't use non-invasive ventilation, and you switch to talking about emergency intubation.

No, that's the reason for intubation.

There are other ways to avoid emergency intubation apart from preemptive early intubation. The question is, why not try those alternatives before going straight to intubation? I've given you multiple sources that agree that the reason they weren't used:

• apparently many young, inexperienced doctors simply were not aware that prone positioning is a thing;
• because of the fatalistic (and wrong!) opinion that intubation was inevitable, so you might as well do it early;
• from a dubious theory that patients would damage their own lungs by breathing too hard;
• and most importantly, to protect medical staff from infection.

Here is you saying that:

"Early intubation should be considered to prevent the additional risk to staff of emergency intubation and to avoid prolonged use of high flow nasal oxygen or non‐invasive ventilation."

Right, and I'll say it again. Early protocols for Covid patients were to incubate early, not because it was good for the patient but to reduce the presumed risk to staff from emergency intubation and non-invasive intubation.