Shadowbinding Shoe, I've now finished my re-read of Mordant's Need, so am looking at the relevant texts to consider the questions/objections you have raised.
King Joyse's smile was as bright and cleansing as the warm sunlight and the ineffable sky.
When he looked at Nyle, however, his smile went away.
He dismounted; he strode toward Nyle sternly, like a sovereign with a traitor to punish.
Then he stopped.
Instead of speaking harshly, he murmured, "Nyle, forgive me."
Nyle's face twisted helplessly. "Forgive--? My lord King, I betrayed you."
"Yes!" King Joyse retorted at once. "you betrayed me--as my daughter Elega betrayed me--as the Congery betrayed me. And because I was betrayed this victory became possible. Everything you did against me, you did out of love and honor. And for that reason everything you did played its part in the saving of my realm. You betrayed me to do Mordant good, Nyle. I failed you. I failed to see your importance, your worth, when my esteem would have been to your benefit.
"I could not have protected you from hurt. But I could have helped you place a higher value on yourself."
Nyle tried to answer; there may have been a number of things he wanted to say. But he couldn't control his weeping.
Both Artagel and Geraden put their arms around him.
King Joyse turned away to address everyone within earshot.
"Nyle has suffered," he announced in a tone both grim and elated, sorry and glad. "Do you hear me? He is not a traitor. He has suffered as the Perdon suffered, and as the Tor suffered, and Castellan Lebbick, because his love is strong and he did not understand."
As he spoke, his voice carried farther and farther, until it reached the walls and the armies, the men of Mordant and Alend and Cadwal throughout the valley.
"A great many good men have suffered and died, among them Master Quillon, who served my purposes when I could risk them with no one else, and Castellan Norge, who served Orison and Mordant and all of you with his life. And with their pain they have purchased a victory which we could not have gained otherwise.
"Remember that they were hurt for us! Remember that we have freedom and victory and life because of them!
"And because all of you fought like heroes!
"Now the world is ours, and we must heal it. From this day, let us make our world a place of peace.'
When he finished, the cheering went on for a long time.
Blind, weary, content--and unwilling to face the rigors of a second journey to Orison--the Alend Monarch had sent his new Contender to stand in his place at the wedding: a man who now could claim precedence over everyone in Orison except King Joyse and Queen Madin, because of his position as Margonal's representative and potential successor.
The new Alend Contender was Nyle.
Arriving for the ceremony, he still appeared perplexed and a bit daunted by his circumstances. But when Kragen had been installed as High Regent in Carmag, Margonal had needed another Contender; and the Alend Monarch had sensed in Nyle a man with a newborn but almost ferocious instinct for caution. Caution, the Monarch had declared, was the fundamental requirement for anyone who meant to rule over Scarab and the Alend Lieges. Kragen had shown himself altogether too prone to risks, and Margonal wished to replace him with someone who lacked that flaw.
Nyle had refused the honor--or the responsibility--at first. He didn't deserve it, he wasn't worthy. Eventually, however, King Joyse had confronted him with a royal command, and he had felt himself forced to acquiesce.
The reports which King Joyse had since received from the Alend Monarch indicated theat Nyle was proving to be exactly the Contender Margonal wanted, despite his self-distrust.
Well, King Joyse certainly didn't cause Master Gilbur to practice his debauchery on Nyle, and likely couldn't even have forseen it, unless it was in Havelock's augery (I doubt it). His public apology, and his proclamation that Nyle had suffered because his love was strong and he didn't understand, may have been enough for Nyle to forgive him for slighting his importance. The ability to forgive is up to the individual, so maybe it was enough for Nyle.
Perhaps the ending with Nyle being a satisfying Contender for Margonal was forced, but then again, maybe Nyle knew now how to balance the desires of the different Alend barons in order to produce a stronger Alend union without showing to much favoritism for any particular Liege. But, what in Nyle's experience would make him better at this? I'm having trouble finding an answer to that one.