The same should hold for The Trayvon -Zimmerman trial.
Not exactly. The members of the Court Martial are all under Obama's change of command. Moreover, the Convening Authority who summons the Court Martial and approves or sets aside its findings is a high ranking officer (O-6 or higher). He is especially sensitive to Obama's wishes because if he goes against them, his military career is over. Obama maintains executive power over the entire military.
In the Trayvon-Zimmerman case, the judiciary is under no such threat of influence but is completely separate from executive power.