Re: Resigning from Starfleet
Her rank may be due to her experience. My Dad enlisted in the Army during WWII, and I think he was originally commissioned as a lieutenant due to having a couple of degrees. He was a chaplain, ending with an active rank as captain, and as a major while in the Reserves.
Dr. Howard, Dr. Fine, Dr. Howard: For duty and humanity! --Men in Black, 1934