Reading Essav’s mind

Essav saw that the daughters of Canaan  were bad in the eyes of his father, so he took to a wife Machalas, daughter of Yishmael, besides his other Canaanite wives. Rashi points out the absurdity in his action, for if he did not divorce his Canaanite wives, what did he gain by taking another? What indeed was Essav thinking?? (See Ohr Hachaim) We suggested that perhaps this last wife was to lord over the entire household, as it says that he took Machalas “al nashav” which can mean not only “besides his wives” but “above his wives”. (Either reading bears out Rashi’s comment that he neglected to divorce the former wives, and the second interpretation explains Essav’s self-justification for it). He believed that if a non-Cannanite was predominant and ran the internal matters of his house then Yitzchak and Rivkah would be satisfied. Not so!