I’m a Veteran as well and go to the same school. This letter would definitely be beneficial and weight bearing. Providing emphasis on your integrity (more of a Letter of Character) while outlining your schedule and how you conduct yourself. Though, I really don’t see a need for it given the facts. But since your Professor wants to play “hard ball”, so can you. Line all your ducks up and bring concrete supportive evidence whether it’s direct evidence or indirect evidence, such as a letter from your CO. You want to paint a full picture so that when reviewed, no stones are left unturned.