To understand why someone would lash out so severely, you have to have a little inside baseball about coaching hierarchy in the US. Having coached in two countries, there is something very unique about the way top American coaches are elevated.
For example, someone “has” confidence, or they don’t. Another person might “have” motivation, or not. When I coached in Denmark, I noted several swimmers when quitting or contemplating quitting would say they had “lost” their motivation. It was almost as if it were a set of keys they had left under a couch cushion and had given up on finding.
Confrontation is a life necessity. If it wasn’t, I’d guess that most of us would hardly ever do it. Constitutionally, I think human beings are designed to be confrontation averse. That is, we are all more or less “pro-social”. Our extent as a species rely on the fact that we have found ways to cooperate with each other at a very high level.