I don’t think OSHA would approve of that many people on the structure.
Back then construction was different and could hold more people than the cheap crap being built today.
I like Travis’ suggestion of electric bleachers, to get the process sped up.
Yep, those folks with a rope around their neck could get hurt real bad.
Sadly, the engineer in me thought “Good point - I wonder how many of them had failures? Especially when they released all the guilty and the forces all acting at once?”