One is a precursor for the other. Being mean and inflexible is their means of avoiding personal growth, which leads to the incompetence. Of course, they are exceptionally competent at being mean and inflexible because it’s what they practice in their lives.

But I think the point they’re making is that it’s moot that they are mean and inflexible if those traits make a good government. It is at least more relevant that they are incompetent at governing; even if both points are likely to fall on deaf ears and even if one naturally follows the other.