Looking at the petition of the big names, which does include many people I respect, I am trying to work out their reasoning.

Interestingly the text does not refer to the case as such, but rather refers to the circumstances (arrested in a third country outside of the US and France) and, bizarrely, the damage it could do to Franco-American relations.

I can understand where they are coming from in the first concern. The second is utterly irrelevant.