Courts martial are predominately inquisitorial rather than adversarial like a civilian court. The fact that the court didn’t find in the prosecution’s favor doesn’t mean they failed or lost, and it doesn’t mean they didn’t do outstanding work; it means that the argument presented BY THE GOVERNMENT did not satisfy the standard for conviction.
Court Martials can send a person to the gallows or send them home free and easy. They are trials in every since of the word. You apparently are not familiar with them.
You can also bet your mortgage that the commander who ordered the court martial, the Convening Authority, wanted a conviction. The fact that he or she only got a photo with a body conviction is not at all what that CA had in mind.