Assuming that the group gains access to the Gwydir Forest metal mines, then that will be a step forwards as there is no access at the moment.
However, as IanA says, if it gets to a stage where the group starts taking over access to mines where unhindered access is already possible, then that causes a problem.
There is a significant difference between "gaining access" and "controlling access" and I would hope that the group both respects this and ensures that the former is what it will be striving for.
From the point of view of the majority of us - and that includes those who have a history of enabling their own access through mechanical means - there has to be a realisation that locking up adits that have not previously been gated is not going to prove popular.
The really big stumbling block would be if people have to be 'members' of a group in order to gain access - although that does not appear to be any part of SMACG's intentions.
However, a sensible balance will have to be struck between the operation of mines by commercial operators and continuing access by leisure users who just want to turn up and go in. The proof of the pudding will, no doubt, be in the eating.
Hello again darkness, my old friend...