Just to be clear, my understanding of sections 25.1 to 25.4 is that they do not apply to private individuals, except to the extent that under subsection 25.1(8), justification and direction can be given to a private individual—for example, to a police agent—to commit conduct that would otherwise be a criminal offence. In those circumstances, that can only occur if a senior officer authorizes it in writing in advance.
With respect to the broader comments of justification and self-defence, and with respect to citizens acting to prevent the commission of an offence, if sections 25.1 to 25.4 were entirely eliminated from the Criminal Code, the right to self-defence would still exist. The right to use force to eject a trespasser from your property would still exist. The right to use force to prevent a continuation of an offence or breach of the peace would still exist. Those provisions apply in various forms to peace officers and to individuals. So it's really not a question of necessity in self-defence.
These provisions are dealing with a very different problem, which in some circumstances may simply have to do with the unlawful possession of contraband. In the narrow circumstances of organized crime investigations, it may deal with providing a credible cover for someone to infiltrate the organization. But they don't have anything to do with the general self-defence types of provisions of the Criminal Code.