So are you saying that people with lower abstraction capacity would do better in work with concrete skills like plumbing, masonry, carpentry, trucking, nursing, etc.
Yes, Peterson is basically saying that. And he is pointing out that people with lower abstraction levels will be happier and more productive in careers that suit their inherent capabilities. He also reinforces the idea that individuals should pursue the highest ideal of virtue in whatever techne they choose in a career; and we as a culture need to get away from our assumption that high IQ equals morality.