Good morning,
Firstly I know nothing about French law but going to court is often dangerous as you can turn out to be the one in the wrong, legally and you ask questions that nobody wants answering.
Before you decide that I am nut case for the following, remember the cyclist found partially at fault when someone walked out in front of him while using a mobile phone.
From what I saw on TV you could describe the accident in the following way.
.......... Part of the cause of the accident was that the cyclist was going very fast on a public road and overtaking other cyclists whilst very close to the edge of the road knowing full well that he wasn't leaving himself any time or room to avoid obstructions in the road.
Of course this is the TdF, it was perfectly normal racing behaviour and the road was closed to other vehicles, but not people.
Had the road been open I suspect that most of use would describe the behaviour of the peloton and supporting vehicles as unacceptable.
So this could open up the question of what, if any, responsibilities of the road user in relation to the safety of others change if the road is closed to public access?
I wouldn't be at all surprised to find that the legal people will have to argue none, from this it could easily follow that road racing on closed roads is not entirely "rider/spectator beware" and that Tony Martin was a fault for not riding slower and not allowing space for a person waving a cardboard sign in the road.
This would not be an answer that any road race organiser would want to see in black and white.
Bye
Ian