Rangers work within the apparatus that is set forth before them....I would be guessing that some person or group put in a formal complaint to NPWS and they had to investigate and deal with said problem. Without any permits, approval on paper it is always going to go against the crag developer....so it not the rangers that are the issue but the whole system that is inflexible to accommodate a sport like rock climbing.
The problem we have that in a real sense you can not get approval for anything, as soon as you ask you will be hit with needs for having public liability covered, environmental impact statements etc plus many hoops that are not designed for your average weekend warrior. The way its setup simply means that climbers will work outside the framework as in its present state is unusable and NPWS will react if need be after the fact....then if we have a case we can then argue against it (though history shows this rarely works).
Generally NPWS will ignore crag "out of sight, out of mind"...but it seem Dargan Arch didn't fit this criteria this has been hit with the ban hammer..a quick Google search shows Dargan arch was in people spot light for some time.