I believe that the Wilderness Area designation requires that only hand tools and similar technology is required for construction and maintenance. You may recall that Roxie wished to get rid of that restriction to make use of chain saws and other machinery more convenient to his sense of wildness.
I would be surprised if the "new" Carter Gap Shelter is in a Wilderness designated area. I know the shelter south of Blood Mtn is just outside of the wilderness area, making the 0.7 mile hike necessary to reach it from the wilderness designated area.