A better explanation might by that by taking this approach, he was tiering the triage, in much the same way that the neurosurgeon in the article's comments mentioned that they were able to "neuro triage" patients sent to them.
I can't begin to imagine handling this type of situation.
1). He didn't know how many people were going to come in or how serious they would be. Triage in MCI does depend to a certain degree on what your facility is capable of and the expected volume and status of patients. If he underestimated the volume or criticality of the patients about to come in he might have put more into the red pod than he would have otherwise. Underestimating seems plausible in this case because this was the worst mass shooting in history in the US.
2). Medicolegally he might have a fear that he would be judged harshly if he didn't automatically try to save everyone.
In a sense, he was correctly applying the rule of optimizing for the most critical resource -- except that in this case, the most critical resource was his ability to triage incoming patients.
I just want to reiterate though... This facility (and this doctor specifically) did a fantastic job. I look forward to the more in-depth case studies as an opportunity to further my own skills in EMS.
Is it implausible that under these conditions someone would be uncertain whether there was no pulse or simply a weak pulse which they missed?
You're absolutely right that finding a pulse can be tricky (though a carotid or femoral is a lot easier than a radial). There are a handful of good studies that show a fairly high degree of uncertainty, even among well trained providers (ER docs, paramedics, etc). This is why breathing is the "real" criteria, and should have been the decision making criteria used in this case.
"Black tags - are used for the deceased and for those whose injuries are so extensive that they will not be able to survive given the care that is available."
https://www.medicinenet.com/script/main/art.asp?articlekey=7...
Again, if you are experienced and knowledgeable in triage please disregard my understanding.
The criteria used by all the major triage systems for a black tag classifications is a lack of respirations (and because he's an ER doc, he's going to reflexively check a pulse).
I don't think my experience is especially important (as you said, this is all googleable info), but I'm a paramedic with a little over a decade in EMS.
https://en.wikipedia.org/wiki/Triage#Conventional_classifica...