Who cares?
He is signed and if he wants to do the best for the team, then he should...Turner was promised Fullback down in Melbourne and look what happened.
As long as Moon is in first grade and playing consistently I don't think he gives a rats...the #13 allows him to be a five-eight in a way where it would suit his game.
IMO Warriors would be contenders with this line up:
1. Wade McKinnon, 2. Denan Kemp, 3. Brent Tate, 4. Jerome Roparti, 5. Manu Vatuvai, 6. Eddie Paea, 7. Liam Foran, 8. Steve Price, 9. Ian Henderson, 10. Sam Rapira, 11. Simon Mannering, 12. Michael Luck, 13. Joel Moon
RES: 14. Evarn Tuimavare, 15. Russell Packer, 16. Jacob Lillyman, 17. Sonny Fai, 18. Nathan Fien
That team has the right mix. Warriors at the moment are very disjointed and ad-hoc in attack. The halves here have the ability to both construct and also create opportunities. That is something Warriors don't have currently and would provide a stable platform for years to come.