Three things about the background of the story and the 'outrage':
- There have been a series of high profile robberies, armed or not, in France, particularly in the south of France: a lot of jewellers are reportedly scared of organized mafias trying to steal jewelleries because they are easy to get money from. This is one case that hides a lot of problems with organized theft gangs/mafias
- Early 2014, there will be local elections to renew mayors so the French political circus is in full bloom right now. Especially, from the far right, who is trying to tie that theft on their usual 'protection of the thief and not the victim' and xenophobic/racist themes so this is rather inflated outrage.
- The definition of self-defense is rather strict in France: this will be the job of the judges to appreciate that. From previous cases, justice is usually understanding on such cases.
He may not have been an immediate threat to the jeweler but he was a threat to his NEXT victim. Criminals being creatures of need, opportunity & habit that next victim would likely have been soon. Probably that night before an investigation even got started. Better to stop him NOW than pray he didn't hurt / kill someone on the next try.
Police forces, judges work only on facts and events that occurred, not on speculations or what-ifs.