You do know that this happens all the time, right?
I was in Paris when an entire block on the Boulevard St-Germain was closed off so that David Beckham and his wife could shop privately in the Louis Vuitton store.
I doubt that the Secret Service would want to deal with shopping crowds.
During the Clinton years in office, The Hildabeast would often fly into Dallas to get her hair done.
During her flight approach to Love Field to arriving at the hair business, ALL highways in Dallas would be shut down by LE.
When the Hildabeast was ready to leave, the process repeated.
It got a point that many radio stations gave PSA’s to warn in advance of her arrival into town so people could plan ahead for the highway closures.