I don't understand why this narrative is always brought up by our fanbase, as if there aren't a ton of ISU students from Chicagoland or the Twin Cities. Maybe it used to a much greater disparity, but I graduated from ISU in 2011 and there were a lot of kids from both of those places I knew. Heck, the 2020 enrollment numbers on both university sites show iowa at 60.5 % and ISU at 56.3% for Iowans. And yes, I'll acknowledge that I'm probably being oversensitive about it as a someone originally from the Chicago suburbs.
I do agree with your premise of hawkeye grads being more tolerable than the t-shirt fans.