Again, you're imposing your own motives and interpretations on Ulfric.
Ulfric can only defend himself in his own words and his own actions.
If we are unwilling to accept them at face value, then we abandon all pretense of fairness or the presumption of innocence.
Because I've played the Stormcloaks quest line each and every time I've done the Civil War, and for the dialog just before the quest to get the crown, he basically says '[censored] the Moot, I'm going to be king no matter what. You there, get me this crown so I really look the part.'
And like with what Mitheldh said, he stacked the deck completely in his favor when you complete the Civil War. He's not an idiot, as many people would like to make him out to be. He knows what he's doing, and he's definitely making sure that when he becomes High King, it won't look poorly on everyone.