Glontan's actions didn't surprise Russell too much; after all, Glontan had harbored the idea of following him before.
It was just suppressed by Baron Gevedas.
Now that he had been promoted to a Flying Dragon Knight, he was destined to vie for the hereditary title of Baron, naturally needing a group of knights to follow him and fight alongside him in the Snowfields to build a career. Glontan's choice to follow was not unexpected.
As the second son of his family.
Firstly, it was not certain that Glontan would be granted a fief; if Baron Gevedas was stingy enough, he could completely withhold a fief and instead send him off to Red Castle to struggle in the Volcanic Oasis on his own. Secondly, even if he were granted a fief by Baron Gevedas, he would be a social butterfly Lord.
Just like Russell's Uncle Rosen, who was such a social butterfly Lord, toiling for the family all year round outside.
He might not even have enough time to train.