Well, politics aside, the thing that cemented his clown status for me was when he was actually going to demonstrate his moonwalking ability at his blackface press conference until his wife stopped him. That was troubling because it wasn't a 30 years ago bad decision, it was present and future bad decisions.
And I have been a part of every football game and every graduation that my high school has ever held. So I can't speak for the "larger schools", but our graduation ceremonies are 35-45 minutes depending on student speech length. A little time for getting crowd in, and milling around afterward. But that happens at football games too. I have never had a football game go under 2 hours, even when there has been a running clock.
Now, fans naturally spread out more at football games than graduation. Walking around, milling at fence. Heading to concession stands. Use both home and away stands, where at graduation everyone tries to cram into the home stands. So it seems to me that it should not be a % of capacity thing, but really a function of how you spread things out. One school system near us is reversing the graduation. Families bring their own chairs, and sit in pods on football field, and graduates are in stands, socially distanced.
It seems like the solution really should be come up with a plan that works for your facility and customs, shoot it by the local health department for approval, and move on. Instead of having one size fits all policy from state.