That wasn't a history lesson, that was an interrogation disguised as a conversation.
Skjold was using his eyes, ears, and maybe even his nose as a lie-detector.
He was evaluating the MC's reactions to each and every single thing that was said. What is agreed with? What is disagreed with? How does the MC feel about this, that, and the other?
That is a skill which fully justifies putting someone in a leadership role, and he's apparently good enough at it to have been raised up the ranks relatively quickly.
Now, I'm NOT saying that his friendliness was or wasn't genuine. That is something we will need to wait till farther into the story to find out. I'm saying that Skjold was multi-tasking. Very good way to justify a lore dump, and it made the motive for it's delivery especially interesting.