Freedom for property owners is a thing of the past. A business owner should be able to give discounts to anybody he wants or not at all.
But you’re assuming absolute liberty to do that. In Obama’s America, liberty is old and tired, and grandpa government is here to stay.
Unless there's more to the story than is in the article (which, of course, is likely), I'm not sure I see a loss of freedom here. The water park offered discounts to church groups. The inner city youth group asked for the same discount, and was turned down. The group complained, directly to the water park, and the water park responded by eliminating the discount. The water park wasn't forced to do so by the government, they chose to do so.
Of course, there may well have been a legal threat of some kind in that second phone call (I'd almost be surprised if there wasn't), but absent that, it looks like the water park simply capitulated to the complaints. Nothing wrong with that - the group was free to complain, and the water park was free to respond as they saw fit.