Retired officers (and enlisted people) are normally subject to the UCMJ. However, they may not be recalled for the sole reason of bringing them under courts martial jurisdiction, EXCEPT for acts committed while still on active duty. However, they can be recalled for post-retirement acts that involve "crimes of national security" as defined by the Hiss Act.

Or, to be more direct, you forfeit your retired pay (after due process) if you reveal military secrets (and that is subject to a whole bunch of 'howevers'), but you may trash the military to your heart's content.