Earlier quoted context omitted.
He's one of very few adults left at that level.
It might be childish, but I think the “act like an adult” (or not) is a good way to frame the bad behavior that’s been so present lately. It encapsulates so much of how I want to describe things. Selfish behavior - this adult is just a child who didn’t learn to share. Mean and vindictive behavior - didn’t learn to empathize as a kid Lying? You’re still a child. Grow up and then join the adults.
Adults push back on aggressors when necessary. Children cower behind the adults.