Are road turnouts part of the National Park system?

OK, I understand that the shutdown of the federal government requires the National Parks and Monuments to be closed.  But I don't understand why officials felt it necessary to block off all the road turnouts leading to Mt. Rushmore and Devil's Tower National Monument with cones.  So, not only could you not visit the parks, but they made it more difficult to safely view the sites from public roads in the vicinity of the parks. 

Unless there is some public safety reason for this, it appears to be a political ploy to make the disruption even more unpleasant.  It is already unpleasant enough (and, of course, totally unnecessary), but why would you want to aggravate people even more?