His clear violation of law was the transfer of documents. Even that, though, assumes there were not traditions of CIA directors carrying around secure documents. At one level, just about everything they touched would become classified. Allowing his mistress to have access to them was different.
However, he was not in the military at the time, so what any military member would have done is irrelevant. He was the director of the CIA...a civilian position. He retired from the Army on Aug 11, 2011 and took the CIA job on Sep 6, 2011. The Army regs did not apply to him after he retired.
Actually, you are wrong. As a retiree entitled to pay he IS subject to the Uniform Code of Military Justice, and he was subject to it on 06 Sep 2011 the same as he was 10 August 2011.
I've included the web address to Article 2 of the UCMJ - just for you
http://www.ucmj.us/sub-chapter-1-general-provisions/802-article-2-persons-subject-to-this-chapter
Pay particular attention to this part:
Retired members of a regular component of the armed forces who are entitled to pay.
So it does matter what would happen to others as there is supposed to be an equal application of the Code the same as there is for other laws. Likely an E-4 or some nobody 0-4 that was found guilty of such would probably also be subject to forfeiture of all pay and allowances - whether Active or retired (though these days, most likely a retired E-4 would probably be a medical retirement).