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).
And this case validates your interpretation: http://law.justia.com/cases/federal/appellate-courts/F2/326/982/279461/
I stand corrected. Thank you.