There aren't many people in that crowd. It looks like the Mr. O really has gotten much bigger over the years.
There are more people on Getbig talking about it decades later than there were in the crowd.

I went to a pro bodybuilding show once where only the auditorium was huge, but only about fifteen percent full. All the people who payed for their tickets were in the nose bleed seats where you could barely see. All the family members who got free tickets were right up front. there were about twenty rows of seats in between these groups that were empty. When men's bodybuilding started, Bob told all the people sitting in the back to come up front. This is the state of bodybuilding today.