since I am not able to speak French, I would make gestures of my ardent admiration of his work, maybe he will feel flattered and even pose for me...being friendly helps
[but the French are notorious for speaking only French even if the person you are speaking with can speak 3 other languages excluding the one you are speaking to him/her in]
I think sometimes if requesting a security guard to move off does not work it is always easier to change angle. Water is flexible and takes the easiest path... I cannot imagine the security guard purposely hopping into every one of your frame...