It's actually in the rules for the JW's that they keep hidden. You can not be disfelloshipped for joining the military. Found this out less than a week ago.
They wouldn't want to go to jail again.
When you vote or join the military, you are disassociating yourself. So, you get the same treatment as being disfellowshipped, but they didn't disfellowship you for doing that, for serving your country or acting within your civil rights.
It's a distinction that rides the technical line between chicken shit and bull shit.