Roddenberry and the other TOS writers never gave much thought to Kirk or the others back stories. They made references that suited the needs of certain episodes and that was it. None of the details of Kirk's early Starfleet career was ever mentioned again. Each new detail had no relation to what was said before. HEck Kirk had a brother who was introduced to be killed off and never be reffered to again!!! Its only the fans and the licsensed fiction which have tried to piece together this random patchwork of Kirk's history.