Just to let you know; there is no outright banning of GCing on all ATC maintained lands. What the ATC wants to do is make sure that caches are not placed in environmentally sensitve areas. Don't ask me what that encompasses. There are other folks who can answer that question much better than I.
There are some areas where GCing is not permitted. As I understand it, the National Forest Service does not permit caching on the land it owns. That includes the AT, and its surroundings. Remember, the AT sometimes runs through and on privately owned land, but mostly it is on NPS-owned land.
What should be done is; if you are unsure of whether there is a restriction on the land you are intending to place a cache, and you know it may be NPS land ... call the ATPO contact: Chief Ranger Todd Remaley at 304-535-6171. The Mid-Atlantic ATC regional office can be reached at 717-258-5771.
ATC volunteers are not responsible for removing caches, but are asked to report their location, and any possible impact on the surrounding area with field notes and photographs through their club to the appropriate land managing agency and the ATC regional offices.
Cachers are responsible for determining land ownership and obtaining permission before placing caches on public or private land. It is common courtesy to ask permission in any event. There are areas that are unrestricted and are considered appropriate for GCing.
That is what I have to offer.