As someone who has been in the past subject to the UCMJ, i.e. I served in the military, I'm careful about using that word. In this case, I believe there would be sufficient cause for the charge. Whether that charge "sticks" is something for the Courts to decide.
But again, as someone who has actively served in the military (although not in either the current set of wars or in the first Gulf War of 20 years ago (but it was close - they called two units like mine), the more details that get disclosed, the more potential damage in terms of 'means and methods.'
On the other hand, I don't think the Top Secret Intelligence establishment had sufficient safeguards in place for someone who thought that the law was being violated to handle these kinds of complaints. That does not forgive Snowden, he could have, for instance, gone to a member of the Senate or House Intelligence Committees (selecting a Member that would have been particularly sympathetic to his position.) Or gone public inside the US, like Daniel Ellsworth did with the Pentagon Papers. Instead, he ran to China and then Russia. Those actions speak much louder to me than any protestations of 'morality.'