Rescue has been proposed several times since the late 60s. The first being by the group that subsequently were given permission to remove the major parts but were declined permission to remove the complete loco. These parts (many many years later) were used by Alan Keef on his locomotive "Taffy". The original plan was to lower it (or maybe raise it?) down (up) the old inclines to a more accessible place for removal. As I said, this was declined.
I believe there have been 2 further approaches to the company. The most recent being by the Penrhyn Railway Trust who were hoping to get RAF Valley involved. This was decided as being impractical due, as has been said, to thermals.