Who cares?
What is the point?
Because I think this observation strengthens my position, which is that a bunch of holier than thou busybodies are going overboard on this issue. You can still buy the merchandise, but by gum we aren't going to let anyone think that we right thinking people would ever approve of it, even if all we are doing is let you buy it in a convenient gift store. You want that awful stuff, go elsewhere for that filth! Some guy shoots up a church, and we zero in on the real problem, which is confederate flag bric-a-brac in gift shops.
Everything in those gift shops can be purchased elsewhere, so there's no need for gift shops at all. You could talk me into saying that we ought not have gift shops on National Park property. Decommercializing battlefields doesn't seem horrible to me. On the other hand, people seem to like souvenirs, and they went to the effort of visiting a battlefield, so what the heck, sell them souvenirs.
So once you have made the decision to sell them souvenirs, the question is whether a confederate battle flag belt buckle is sufficiently offensive that it simply ought not to be allowed as a souvenir of a visit to the place where it was flown for its intended purpose. Apparently someone somewhere decided they really had to register their indignation by getting that star spangled saltire off of the shelves at the gift shop.
On the other hand, whatever workshop in China that actually produces those things is probably working double time this week. There's nothing like an attempted ban on something to make sales soar.