a perfectly safe decision was made - by the captain.
I don't agree with that. Neither the Captain, nor his Management have the ability to say if any engine is likely to fail or not. If they had this ability they would have replaced number 1 engine before the first flight.
Flying almost 3 hours over Europe with 500 souls and an engine out is not a responsible decision. There were many airports suitable for a landing along the way. Why return to Paris?