The dilemma here as I see it & this is only my humble opinion, JFK asked for the car security bubble to be removed so that he could be seen more clearly. 1st bad move, the security guards were supposed to be riding on the back of said limo to protect his back , it can be seen quite clearly they were told to get off ,2nd bad move, their confusion after this order was given is clear to see you can also see JFK is aware of this going on. Conjecture . Did he also give this order? Conclusion, yes! For the same reason. 3rd bad move. Don't forget, our Royalty work on the same lines they want to be seen by all who have waited in all weathers to see them, they & only they have the last word, they are advised by security but they alone make the final decision.