I think it is just as likely that one of the Palace/Clarence House/Kensington Palace leaked the notion that Guy Pelly might be a godparent to see if it would fly.
I don't find it unusual that William might have proposed him, for the following reasons.
1. Guy Pelly has been a friend to both William and Harry for some time. Not sure when they met, but it was years ago.
2. Pelly has taken the fall for William, apparently--I speak of the time when Harry stood accused of using drugs; some think that it was William, not Pelly, who introduced Harry to same.
3. According to Katie Nicholl, of the dubious Daily Mail, who wrote a book entitled ... William and Harry, in 2010, Guy Pelly stood by Kate during the 2007 breakup.
4. I know nothing of his background, but it is clear that Pelly actually works for a living, and I rather doubt that nightclubbing would have been something his parents would have chosen for him if they had been well-heeled enuf to offer him an alternative. He may well be an entrepreneur, a self-starter, of necessity.
5. He may sometimes drink to excess, but who doesn't in the William-Harry gang--and if that is his only misdemeanour, then he is well ahead of some of the royal circle of friends, several of whom were more-or-less foisted upon William and Harry by their definitely morally dubious Dad.