MC's history degree seems useful but maybe a PoliSci minor woulda been handy.
IMO he showed his hand way too early. There was no rush. He could have kept his cards closer to his chest for a bit, and built up a stronger hand (bargaining position) first. Maybe it was for the sake of expedient storytelling, but joining a kingdom should never be done without thoroughly understanding their motives, their allies and enemies, what they stand to gain from you, what you gain from them, specific rights and obligations, etc. This is not the time to skip past the terms and conditions page and click OK.