As the senior NCO of an Infantry battalion, I can tell you that commanders do charge service members on dumb-ass twitter and waste-book postings that bring discredit on the service. And I have yet to see one overturned on appeal.
There is a special look on a soldier’s face when you show him the stupid picture he posted, and read him his rights. Last one I was involved with cost the soldier two ranks and half-month’s pay for two months.
Article 15 or Court Martial? Because if you are taking pay I think that’s CM: but then again, I mustered out in ‘93 so what do I know.