If leaks can be justified, then it becomes a moral question of what justifies it. For some, adultery is enough to justify a leak, for others it is not (some of which do think the government wronging many people is justified). The core question is one of how bad does a leaked behavior need to be for a leak to be morally justified.

As far as it not being illegal, any moral system that determines morality based on legality is a system I find fault in.