What oath? The only oath he was required to sign AFAIK is the Oath of Office: one defending the constitution, not the corrupt inbred military-industrial-complex that's grown up. His oath read:

"I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I take this obligation freely, without any mental reservation or purpose of evasion; and that I will well and faithfully discharge the duties of the office on which I am about to enter. So help me God."

Source: http://www.newyorker.com/news/amy-davidson/did-edward-snowde...

I don't know one way or another about a Medal, but this man has upheld his oath, and he did not allow reservation or evasion to deter him in it discharging it's duty. So help him.

Breaking the law =/=> doing something wrong.

Nothing in your post is responsive to parent. Snowden broke the law and should be pardoned because he did it to fight far worse lawbreaking.

Yes. But that's just my opinion.

That was 40 years ago. We have had many pardons since.