There is NO advantage to be gained from starting on a low branch of the tree when you can instantly jump several branches higher and start as a WSO. You would just be wasting time, seniority and money. If you're deemed suitable for a commission as a WSO ... just bloody GO FOR IT!
I wouldn't have said it was a lower branch, I'd have said it was a different tree. If he/she wants to be a chinook crewman, a WSO (effectively Nav) commission is not the path he/she needs. Otherwise, agree with the sentiment.