I'm guessing that Mt. Rushmore was closed to visitors, so the visitors were pulling over to view it in another location in such numbers that it became a safety hazard on the highway. And the police were probably South Dakota state police, not connected with the federal government.
Then they shouldn't be doing 0dumb0shit's dirty work for him. More likely they are card carrying RAT bastard demoRAT union members, and they are harrassing sight-seers out of the evil that naturally flows from RAT bastard socialist, union, liberal demoRATs. If a Republican president at any time had ever acted this way in any aspect, there would be a thunderous cry from both demoRATs & weak-kneed Repubs to impeach a Repub president. So far, there has only been a handful (less than 10) Repubs who have made any criticisn of 0dumboshit for closing open air parks or memorials.