That, and also saying that just because you hold a reservation (or several) does not mean you have an absolute right to access the land. They can cancel anyones reservation at any time. Not saying they will, not saying it would be good customer service. But they have put that into the fine print so if they need to, they can. It could be because of capacity, because someone already gained access to the land, because whatever.
We're also out-of-state, so were extremely fortunate to be able to make the one reservation. I barely got in before our single day to see it was sold out as I read on here - May 31st, so I'm thanking my lucky stars. I doubt they're going to limit access for capacity since, as you said, they do have those numbers and it's restricted access. But they're putting in that fine print so if they tweak their policies or something drastic happens, they're covered.