He would be the rarity in a suit. I’d say just a nice polo, if he wants to fight the Iowa thing a bit, wear a red polo with no ISU markings.
I didn’t pay attention if there was any Iowa stuff at my sons because I was just paying attention to my kid. Will be at another in December, so I will look to see if any hawkeye stuff then. I wore ISU stuff, but it was ISU and I’m a grad so that one was a no brainer. Btw, my son said my diploma is much nicer than his. It’s actually Cardinal in color whereas his is red. Exact same degree but just 28 or so years later.
Mine is just black and white.
And on a stone tablet.