Couple of things:
1. Being moved from wing to centre is not a demotion. The need to drop back for kicks means wingers get more opportunities to run the ball than do centres - they get a possible kick return, then all those runs on exit sets as their teammates get back onside. Every week Ken Sio makes more runs than any of our other outside backs, for example. The reduced defensive workload also helps.
2. Blair is obviously being considered for both positions anyway. He's got all the goods physically - height, strength, agility, speed - so why should he be limited to just one position? Having him able to play both positions is good for our effective depth.
3. The centres in NSW Cup are obviously both too slow for the wing, whereas Blair isn't. So it's natural that he should play there.