Just because something is constitutional does not make it ethical.

Irrelevant when it comes to whistleblowing and legality. The government could not function if people were justified in releasing all information they disagreed with. Surely the set of information related to actions that no one disagrees with is empty or nearly so.

I don't think it's as black and white as that. Maybe the NSA spying on some overseas entities isn't strictly illegal. But to understand the bigger picture of their all-encompassing reach and sheer pervasiveness better emphasises their wrongdoings on US soil because it helps explain why the NSA's general mentalities of 'we have the right to collect ALL of the information' and 'we are above the law' exist.

Am I saying I think it's outright justified? No, because I'm honestly not sure. I am however sure that it's not as black and white as 'legal' vs 'illegal' when it comes to whistleblowing because the extra infromation helps us establish a context and understand a sense of scale of the wrongdoing, for example.

edit: Here's an example: It's probably not illegal that the 'official' estimates of civilian deaths in the Iraq war were likely far lower than the reality. Assume for the sake of discussion that this was intentional. Having a better understanding the more realistic magnitude of civilian deaths helps the public understand the realities of such wars and helps them make more informed decisions on whether they're comfortable with the actions of their government. It changes the context of the Iraq war and may go from 'we were justified in doing it' to 'it wasn't worth it' for some of the voting public.

I agree with you. I don't have a clear opinion of Snowden. The point was just that those who try to claim he was just blowing the whistle and therefore shouldn't be prosecuted or pardoned are missing the point of whistleblowing with respect to legal protections.