It has logic. He now has a 10-man militia and one more tribe. Who knows how many will be following him tomorrow. Gradually he becomes more popular and Athia, Liandra and her father can help him. But there's also the possibility of him being heir to one of those thrones, which would be pretty cliche.
The game so far is an underdog tale, so I'd rather assume that the MC travels the vales and contribute to each region solveing their biggest issue and rewrites the first Emperors/Kings tale. He'll become (in)famous and eventually be able to make the people raise against the 2 Kings sending them into exile while reuniting as a single nation.
The MC is no politican so I don't think he'll be a King, but rather a Heroic knight retiring in the countryside to live the rest of his life happily with his Harem, which at that point makes the whole population of a big village.
Includeing the former Queen and Crown Princess of the fallen King eric, in order to protect them aginst repressions of the common people that suffered greatly from that war.