Pure speculation, but I could also easily see it just being kids from other nearby schools that heard about a protest at Columbia and rode the subway up from NYU, or CUNY, or any number of schools in the area. Technically outsiders at that point, but I wouldn’t really consider them as such.
Anyone know what book this is from? I’m guessing from Zdarsky’s run of Batman? Feels like a gag he’d write at least.