Bear in mind that Ishgard is heavily bound in traditions of the church. They believe that whoever wins a trial by combat was sanctioned by their goddess, and to go against that means going against the church itself. No one is willing to risk that. And defeating two members of the Heavens' Ward, the personal bodyguards of the Archbishop himself, in fair combat, is a hell of a sign to stay out of the way.

Also remember that the Scions, and the Warrior of Light in particular, had recently (in-story) gained considerable favor with Ishgard for defending the city from Vishap and the Dravanian Horde on the Steps of Faith. You're not just some random mercenary wandering in; you've already proven that you stand against the Horde and shown to be a capable warrior. And more recently than that, you've helped root out heretics in the Western Highlands and saved the son of a noble house from the Vanu Vanu. You've got a fair amount of cred beforehand. So there's no shame for the knights who lost the fight. (I mean, sure, Grinnaux wasn't happy, but he's an asshole anyway.)