I think the more important question is “What would you do with a gun at an amusement park?” With all the rides that spin you around and flip you upside down or whatever - I don’t think a gun would stay in its holster very well if you were going on a rollercoaster or something like that. Or, if it was in a purse or fanny pack or something, you’d have to leave them on the platform while you rode, which wouldn’t be very safe either as there would be no telling who could get their hands on them. Of course, you could lock your gun in a locker while you went on the rides, but that would entirely defeat the purpose of bringing it in the first place.
With a fanny pack, you'd just move it around to your front, unless you've got belly like mine, in which case you might not fit on the ride in the first place. Or for various reasons you might not want to go on those rides, or you could have someone else in the party hold the purse/fanny pack while you go on the ride, and they you hold their "stuff" while they go on the ride. That's a common enough thing to do anyway, gun or no gun.
But this guy may not have been going on the more violent rides anyway. I didn't the last few times I went to such places (Sea World, San Antonio and Six Flags-Arlington Texas)due to being too big, and having a bad back on top of that. I still can go on some rides, and at Sea World I really go for the shows.
In a rational world, the park might provide a secure storage facility if they are going to ban or restrict concealed carry, or even if they aren't. Most of the worst incidents, such as this one, happen *outside* the gate. In the parking lot or on the way to it.