Must be policies regarding these. "Hyperactivity" reads flagrant policy? A small earth moving machine feels over the top to me.
I don't think they're exceeding what they have permission to do or that what they aim to create is particularly unreasonable (though I hope it doesn't expand the area it covers much more) - they just don't seem to have any inclination to rest on their laurels once they have x miles of trails built. And it seems clear that the trail network they're incrementally creating is and will be meaningfully better than the one that used to exist - maybe less technically demanding in some ways since they're smoothing out some of the rocky and rooty obstacles but they're adding plenty of manmade obstacles and the new trails are definitely better designed from the point of view or erosion control than what used to be there. As a mapper, it would be nice if things would stand still is all.
Also, the excavator I saw really is tiny - three feet wide, maybe a bit less. It looks pretty appropriate to the task of gouging a perfectly level path a few feet wide contouring along and gradually ascending or descending a slope. Search me as to whether they use it or something else to start a new piece of trail in level areas.