Actually the system will protect against this, maybe not by design but it works.
In my area we have a section of interstate undergoing a major rebuild, two weeks ago a rather heavily trafficked interchange was closed for a six week period. In anticipation of the closure I disconnected the ramps and the cut the road under the freeway (as that section of road is also closed) and did it timed for an update to have the closure go active a couple days after the interchange closed. From the time I made the edit until the interchange closed and a couple days afterwards I was seeing multiple UR's from the system because the roads were not connected yet traffic was flowing through the disconnects.
Thus the protection. Someone could try to be a joker or a jerk, but if any editors are paying attention to the area, they'll see UR's popping up almost as soon as the edits are made, and thus will most likely be able to fix the problem before it goes live.