The guy's not just some caricature of evil though, there's a reason for the way he is, and that's changed in this AU.>>91698492
If he got what he wanted, I don't think he would be one to subject his children to those kinds of stresses. Most parents don't want their children to experience the hardships that they went through, if they're avoidable. If it can't be avoided, they'll usually try to teach them how to deal with those hardships instead.
The paranoid part of him might believe the peace could just be temporary, but I think he's someone that would value the happiness of his family and would try to be realistic about it instead of pessimistic.
Even if he did perceive a threat to peace and intended to teach Star how to use magic, he may have been assassinated like >>91698380
said before he had the chance to do so.