Knowledge and intent seem important here. If the developer had specific knowledge of a someone using their service to commit a crime and did nothing to stop it,

Knowledge and intent seem important here. If the developer had specific knowledge of a someone using their service to commit a crime and did nothing to stop it, then they could be an accessory to that crime. If you sell a weapon to someone knowing ahead of time that they are going to use it to rob a convenience store, you are not innocent.