I don't see anything wrong with having a more experienced pilot "looking over your shoulder". In fact a basic license is just a ticket to learn. Unless there is an insurance stipulation that the owner must be in the seat normally occupied as primary pilot, I say run with it--log the hours, get the experience and move on with your career objectives.
I spent 2 years "pulling gear" for ex-Air America and Continental Air Services (Viet-Nam & Laos) guys in Alaska and much of what I learned is probably why I'm still alive today.