If I'm not mistaken, his preferred term is "Dear Leader" (or maybe that's some other delusional dictator).
“Our leader? I thought he was our president.”
I believe for a while Michelle was making comments about how her partner would make a great “ruler,” until one of her handlers took her aside and gave her a short lesson on US civics and the aversion of Americans to kings and such.
It may have been something like Truman calling fertilizer “manure” at an Independence, MO flower club meeting: Someone complained to Bess and she said, “It took me years to get him to say manure.
Mookie was either just saying what she was thinking, or maybe she thought “ruler” sounded better than what she was really thinking.