Yep.
If you ever bought a boxed set since 2008, they've included those "Introduction to the Battletech Universe" booklets separate from the core rulebooks. I find those are good for the absolute layman, as they give you a good idea of the existing fluff up until the now-ish period, and about the Major successor states, and technologies.
After those, some of the Era Reports are nice bathroom readers, and they focus on the basics of each faction.
TROs are always a must-have. I always found that I was more likely to get attached to fluff behind a 'mech than fluff for a faction. It might also help him to get an idea of what kind of gear each faction has, so that if he's not choosing a faction based on fluff, he can at least pick a faction based on equipment.