I'm in between Manning’s original statements-by-his-actions and this contrition. (1) Airport users and news watchers knew, or IMHO ought to have known, a great deal about the several threads behind the growing security state: (1) Power politics just can't be nice; we may one day have species-wide law IF we can figure out how to have one government and not be oppressed, but it's a jungle until then. So the revelations ought not to surprise; (2) Government has a propensity to avoid embarrassment at almost any cost. Obviously silly and wrong yet in part somewhat excusable: graceful acceptance by most of at least the general legitimacy of authority is fundamental to authority existing without either stark oppression or the sort of anarchy that can kill a major fraction of the whole people; and (3) individual empowerment is a new thing, with the part that applies to the ability of seriously angry people to essentially wage war like a State being a real threat, one that properly scares people.
I think we knew about most all of it, or ought to have, making almost all of the revelations not revelations at all. Except for the disclosure of sources and methods, this could endanger the lives of people acting from conviction and in our interests, not a good thing.
In sum, Manning was no traitor, yet if his apology is centered on the possible risk to the lives of agents and tipsters; it makes sense that he would now say that.