5/ To the extent that "the whole town" turned out and rooted for the same team, Sasse is figuring authentic Americanness as involving small, racially and otherwise homogeneous communities.
6/ Because in heterogeneous communities, we have never all rooted for the same team. That's partly because, in racially heterogeneous communities, schools have always been racially segregated--first de jure, then de facto as a holdover of de jure segregation.
7/ And, of course, even plenty of white Americans didn't turn out (or did so only under pressure) on Friday nights to support the team. Some just don't care for football. Others found the performance and celebration of combative masculinity off-putting.