Actually, US v Throckmorton weighs against overturning Xiden’s putative victory: “Fraud vitiates every thing, and a judgment equally with a contract; that is, a judgment obtained directly by fraud, and not merely a judgment founded on a fraudulent instrument; for, in general, the court will not go again into the merits of an action for the purpose of detecting and annulling the fraud.” - https://www.law.cornell.edu/supremecourt/text/98/61
I don't think it says what you think it says.