Its not up to the ATC. The AT is a National Scenic Trail administered by the National Park Service. While the ATC does a ton of work to support the AT and no doubt has influence with the NPS, it has no statutory authority to move the trail. As far as "stringent" regulations, every thru who has done any planning knows that these regulations exist and they need to deal with them. Yet every year we get the same whining and complaining from a small but vocal and entitled subset of thrus. Until the NPS reviews and changes their regulations, hikers can either follow them, violate them and risk the penalty, or if they feel that strongly, just bypass the GSMNP.