There are many words to describe those on the path of energy refining. These words include cold, calculating, obsessed, and logical. They are not emotional beings like those on the path of body refining.
He learned about these things from his mother after reaching the ninth transformation. So he understands why she behaves how she does sometimes.
He can complain about it, but he can't complain too much because it is somewhat of a good thing that his mother is on the path of body refining.
It is because she is on that path that she wanted him to do well only for her to give up on him when it looked like he didn't stand a chance. Then she came around and became dedicated to helping him become stronger.