(/sarcasm) Gosh, if we can't go after retirees for things that have nothing to do with their military service, however will we maintain good order and discipline? (/releases clutched pearls)
Seriously, claiming jurisdiction over anyone because they nominally chose to take advantage of the *only* retirement plan available after 20 years of service is insane. The fact that the government is straight-faced using it to try execute one of those people (see U.S. v. Hennis) is egregious. The logic is absolutely perverse: 'You volunteered to serve in the military therefore you have fewer rights than an ordinary civilian for the rest of your life...'
Correction: Hennis committed his offenses on active duty, Larrabee did not (apologies for conflating the two).