Consider an analogous situation: the developer knows the email address of a user that pirated their software. They send them a link to a trojan that will wipe t

Consider an analogous situation: the developer knows the email address of a user that pirated their software. They send them a link to a trojan that will wipe their hard drive when run. An illegal action is still illegal when it is done as revenge for copyright infringement. From an ethical point of view, consider that the damage could be inflicted on innocent third parties. E.g. if a negligent employee runs a pirated game on a computer that controls medical or industrial equipment.