No one other than Williams and his advisors know for certain what his intentions are in 2013, but there is a weight of evidence that creates reasonable doubt he'll be playing rugby. It's a professional hazard of top flight football that there will be speculation and rumour - with Williams, supposedly, all but committed to joining the Roosters next season.
Definitely true is that Williams is off contract with the NZRU at the end of this year and is suitably cagey about his plans. Because of that uncertainty should he have been asked to be an ambassador? Isn't it likely, maybe even probable, that the NRL are delighted to see Williams in such a role with the NZRU?
Will they be sitting back, just waiting for hundreds, maybe even thousands of kids to switch their allegiance to rugby league if and probably when Williams jumps codes again?
It's not a question of ethics or any suggestion Williams isn't anything other than sincere in his role. But the reality is that kids engage with superstars. They will fall for Williams more than they will fall for rugby and wherever he goes, they will follow.
For the moment, that's a risk the NZRU is prepared to take because they can't second guess what Williams will do. They will back themselves to persuade him to sign on for longer and ward off the looming threat of the NRL.
That's going to be a big ask although they can be comforted by knowing that while they have taken a major risk with Williams, they could potentially benefit from a major reward if he stays.