While a lot of what he did was very unnecessary (He comes off as a rather entitled person,) I really can't believe how poorly Six Flags handled the situation. Even at Walmart, they know that the customer is always right. In my checkout lane, there have been several times where customers have had price-match requests that completely violated our policy, I said that I can't do it, they complained and said that they wanted to speak with a manager, I called the manager, and the manager, although agreeing that we do not honor that certain type of price match, did it anyway so that we wouldn't lose the person's business.
Simple mathematics. Either give them what they want and lose $20 or so on the one item that they wanted to price-match, or lose hundreds (or even thousands) of dollars because the person is never coming back to your store again.
So, yeah, Six Flags apparently doesn't get this. A simple matter of not giving someone their seat, and every level of management refusing to offer him this simplest of requests, ended up costing them possibly thousands of dollars because he and his family are never coming back to a Six Flags park again.