Whenever a Catholic group rents the whole park. Things like this always are blown out of proportion. Great America is a business that would have been closed today, but they do let groups rent the park for a fee. No one is being excluded as they would have been closed today anyway.
That's correct. If you have the cash, anybody can rent out an amusement park.
This weekend is Proctor and Gamble Dividend Days at Kings Island. If you don't have tickets through P&G as an employee or retiree, you can't go.
Park rental, as well as group admission, is quite common, but not really the issue.
Obviously "admission" policy is set by the renting group, properly, but I've never seen a statement similar to ENTIRE PARK ALL DAY, FOR MUSLIMS ONLY! on these promotions. Guests who've acquired tickets are generally welcome.
Equally important is the nature of the group, which in this case appears to be subversive. Great America can rent to them, they can rent to the KKK too. And they can refuse. When they rent to controversial groups, they're open to criticism. It's perfectly legitimate.