The secular world doesn’t require moral authority to lead. It helps, sure, but it’s not a stopper if you can’t manage to project it; more of a “nice to have”, really. Luck, slickness, charisma, raw power, a media propaganda machine, a dad with name recognition, or some combination thereof will generally get you into a leadership position even if you’re otherwise horribly unqualified.
Ask Mr. Biden if you doubt that one. If soundness of mind and coherent speech are not obligatory to serve as President of the United States, I doubt self-restraint is anywhere near the list.