That's not how triage works. It's literally an algorithm. If the patient doesn't have a pulse, or isn't breathing, they're a black tag. There is a fair bit of wiggle room between the other triage classifications, but dead is dead in triage.
"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...