Is this veiled threat on line?
I searched for it and indeed this is true. Not new either...
Those subject to the UCMJ include “Retired members of a regular component of the armed forces who are entitled to pay”
Look at 802 (4) at the link below
http://www.au.af.mil/au/awc/awcgate/ucmj.htm#802. ART. 2. PERSONS SUBJECT TO THIS CHAPTER