You're right in any case, you're the cash paying customer. If you want the oil changed just tell them "I want the oil changed." If your service advisor has a problem with that be sure to let the Director of the Service Department and the Customer Relations Director know you would like your oil changed, but the person you spoke to doesn't want to do it for you. I promise you they will flip their lids and oilz will be changed.
Besides, your advisor sounds like a nit-picky, OCD case. A few hundred miles either side of 23,000 miles isn't going to spontaneously implode the Universe.