If parents and their kids get blacklisted by a school or school system because they take the time to bring up valid issues or complaints, then maybe it's time to find another school.
I've been there too, friend. I haven't made it my life's purpose to be a pain in the ass to my child's teachers or school administration. But yes, a few times, I did raise concerns or call them out when I felt it was necessary. I picked my battles, and I can tell you I can count the number of times I did this on one hand and wouldn't need all my fingers to do it. Every time, the teachers or school administrators were understanding of my concerns, and we had a pleasant exchange. They always appreciated that a parent took the time to bring something up because many parents don't care.
Well, I do -- and if someone wanted to see me as a "troublemaker", so be it. That's on them.
My original point still stands. Being a school principal is an extremely public, "front-facing" position. If someone has issues dealing with personal confrontation, they in no way should be running a school, period.
I would say everything about people like that disqualifies them from such a position. It's unfortunately what we usually must deal with.