Interesting. Our HS (baseball) coach would kick guys out (that were active in another sport), of his open gym for baseball. It always pissed me off."Open Gymnasiums or Facilities Member Schools 10.1) Regulations 10.1.2) The school may designate the sport or sports that will be played during the free play period, but may not limit participation to a select group of students from within the school. The school may also designate the grade levels involved and may limit participation to students enrolled in the school."
Straight from the OHSAA handbook in reference to open gyms. It's available for viewing on their site. The school may not limit participation in open gyms/conditioning to a select group of students (ie. those not playing a winter sport). Athletes involved in winter sports are free to attend an open gym for a spring sport. Don't rely on what a slideshow says or does not say.