France defining itself as anti-death penalty is fairly new and not a universally held French belief. The death penalty was only abolished in France in the 1970s. There was a poll done in America and France after the capture of Saddam Hussein.
In America roughly 60% supported the death penalty (I expect it would be a lower number today).
However if the question was asks as Does Saddam Hussein deserve the death penalty the answer was nearly 80% positive.
How about in France? Not as different as you might think. 40% of the population supported the death penalty and when the question was ask regarding Saddam Hussein the number was 60%. (Which means that under certain extreme circumstances the French people actually supported the death penalty and maybe still do.)
Given this poll, I think almost 2/3rds of the French people would probably support the extradition of Bin Laden (in other words be OK if Bin Laden got executed). This is not the case where French elite opinion (which is anti-death penalty) would draw a line in the sand and refuse extradition on French principles.