The MC uses all of this as evidence he has been wasting the kingdom's and his precious time, and it makes the king decide to immediately execute this guy when the match reveals that he has specifically gone against the king's orders time and time again because of his pride. The execution happens right in front of the first academy's students, so they all become very nice and obedient, and no nobles whine about being used as dungeon miners. The point is, Matty doesn't need this dude alive; he's just an eternal hindrance, like his older brother. What he needs are the "glory" crest production squad of useless nobles, and he and several others have decided this is the best way to shut up any and all dissent.