College football is common ground
Context
Dan's argument is that college football can steer awkward or polarized conversation into something personal but relatively neutral. Unlike a city with one dominant pro team, a college-football room can contain fans through school, family, spouse, geography, childhood, or pure adopted allegiance.
That makes the sport socially useful. Asking about someone's college team often opens a story about where they went, who they watch with, or how their fandom formed, rather than a flat agreement that everyone in town roots for the same pro franchise.