Given the level of duplicity I have seen the French capable of, who is to say the French did not kill him in a ploy to create FUD (Fear, Uncertainty, and Doubt). I put nothing past them.
This article is long on assumption and short on facts. One assumption I refuse to make is that any French intelliigence assets were working in tandem with US interests.
In fact, I am inclined to turn the whole conclusion of this speculation on its head.