I agree, it is perfectly normal to publish presidential parade routes ahead of time, there is nothing nefarious in that.
The original plan was to have the limo roof up. But JFK and other presidents had sometimes ridden in open limos, so it didn’t seem like a big deal at the time to put the roof down.
https://www.dallasnews.com/jfk/jfk/2017/10/26/bubble-top-saved-kennedy-answers-strange-story-jfks-lincoln-limo
“Would a bubble-top have saved Kennedy? More answers from the strange story of JFK’s Lincoln limo”