Seems like at a certain point, the authorities would just topple things in a controlled manner. Kind of like how avalanches are preemptively triggered when the area is clear of people.
As opposed to the alternative, which is to let gravity resolve it, mashing a few tourists into paste in the process.
That might make sense if there are indications that the rocks are moving, but with these two examples from NH there were no warning signs. Cool looking rocks are going to gather a crowd, the risk is part of the attraction.
Yeah, I think that’s what I’m saying. If at some point the authorities detect enough change that it’s no longer prudent to tempt the fates, then down it comes.
Until then, it’s every man for himself. 
There was a CBS Sunday News segment on the system of supporting cables for The Old Man of the Mountain, which showed an inspection team making sure everything was OK. This was well over a decade before it collapsed, and things looked secure but shaky.
When the fac finally collapsed, it wasn’t because of those well-supported rocks with cables. It was because the lowest tier of rocks had been undercut by erosion, and no amount of concrete was going to hold it in place.
I vaguely recall reading 10-15 years ago about a rock arch(?) out west (utah?) where the authorities did close the trail because it had gotten noticeably unstable. It duly collapsed a couple years later. This was also not an environment where there was any practical way to stabilize it, and hence no effort to stabilize it.
Punchline being sometimes they can and do close access.
There an endless numbers of under-cut cliff edges in Arizona/Utah/Colorado. I will walk on some of those boulders, but not if I can see how precarious they are…
Of course, if a random civilian takes it upon themself to take care of a scary rock, they can face legal repercussions. At least, in a park. At home, it might be different.