Your questions are well placed and would be difficult for anyone to answer satisfactorily. Prior to April 16, 1862, the only way any man could have entered Confederate service would be as a volunteer. Following the fall of Forts Donelson and Henry, the Governor of Mississippi was asked for more troops, and almost certainly citizens were told that unless volunteers stepped forward, some form of draft would be required. Still, no none was forced to enroll up until the law went into effect on May 16, 1862.

The writers want a story they can sell, and it sounds better for Newt to have been in consistent opposition to the Confederacy. As you've demonstrated, facts undermine that assertion. People are usually more complex than that. It makes much more sense for him to have become discouraged with Confederate military leadership during the retreat at the end of November 1862. A lot of men left the ranks following the defeat at Corinth and Grant's advance into the central part of the state.