I personally do not; my area of expertise lies in military intelligence. HOWEVER... my unit has two J.A.G. officers attached to us, and I have put the question to them just now, as I am performing military duties currently. In their professional, legal opinion, Article 104 of the UCMJ only applies to civilians in those instances outlined under U.S.C. Title 10, Chapter 47. If the civilian in question is not affiliated with the US Military at the time they leaked the classified information (and again, this is according to two J.A.G. officers who have been to law school and whose job in the unit is to interpret military law), then they are charged under U.S.C. Title 18, which is US Federal Law, not the UCMJ. The civilian in question must have an identified, previously agreed upon affiliation with the US Military for the UCMJ to apply.
To the best of my knowledge, every civilian who has been accused of espionage or leaking classified information in the history of the United States has been tried under U.S.C. Title 18. There is no legal precedent currently to show that a civilian with no military affiliation has EVER been charged with violating Article 104 of the UCMJ; indeed, there is no indication that ANY civilian, military affiliation or no, has ever been charged with violating that article.
I would also point out that what Justice Stevens may or may not be implying is solely your interpretation. In addition, Hamdan was NOT being tried with a violation of Article 104; according to the
documents released by the Supreme Court, he was being charged with one count of conspiracy. Conspiracy is a violation of Article 81, not Article 104. To add insult to injury, Hamdan is NOT a US Civilian who leaked classified information; he is a Yemeni national who was captured in 2001 and turned over to the US Military before being transported to Gitmo in 2002, the implication being that he was considered at the time an enemy combatant. That is extremely different from Manning's case, and is even further removed from the idea that US civilians might be subject to Article 104 of the UCMJ when there's a perfectly sound Federal law already enacted by U.S.C. Title 18 that they ARE subject to.
Maybe you should research a bit more before pulling examples out, just to be sure they're actually saying what you claim they say, hmm? It took me fifteen seconds on Google to find the actual opinion filed by Justice Stevens where the circumstances and charges against Hamdan were provided. I seriously suggest that you find a different expert to source, as this Professor Benkler is clearly biased and does not begin to understand military law.