First of all, you don't seem to grasp what private means in this context. One thing it doesn't mean is "owned and operated by a government," which Ontario Place has always been. Ergo, not private. If you really want to split hairs, the Province is merely leasing land to Therme for 99 years but for all intents and purposes, Therme is most definitely private. Whereas, to recap, Ontario Place is public.
Oh, but you're using "public" to refer to access rather than ownership? That makes no sense but OK. But tthen you're still wrong because it was publicly accessible then and will still be publicly accessible; you just have to pay. Whether the difference is "material," is perhaps the subjective crux here, but I don't really think so. If it were, we could start splitting hairs of how much it cost to get into Ontario Place vs how much it will cost to get into the "wellness centre," but that would bore both of us. (Not boring: you calling a "wellness centre" the architects tell us is a public good necessary for mental health and such a mere "amusement park.")
Now, it is true that for much of its existence, Ontario Place required paid admission. But not always. There were, for example, times where admission was free and you had to pay a la carte and there were times when you paid admission and everything inside was then "free." And of course it has been "free" since it closed and reopened in its current 'passive park' version. The fact that Ontario Place charged a fee and High Park does not, doesn't change the fact they are both public but anyway, I don't think we need a breakdown of all the various ticketing schemes they tried over the years in order to come up with some kind of number that quantifies Ontario Place's Material Privateness.
All that matters here, which is perhaps what you are missing, is the difference between the government operating a public facility -whether it's Algonquin Park, Ontario Place or the Ontario Science Centre - and the government selling/leasing a facility to a private, for-profit company to operate. I will give you benefit of the doubt that, despite your "argument," you are aware of the difference here, between for-profit private corporations and government agencies. It's a rather more important issue than whether the existence of an admission fee means there is a "material difference" in public access, which is meaningless and/or beside the point, really. It's either not understanding the issue or trying to change the subject and it won't accomplish anything.