So, personally, I've been involved with debconf orga for so long that I'm not sure why I was not a chair in the first place.
However, I don't have any desire of claiming a position of power right now. So I'd be fine as a dc15 reviewer.
Moray wanted the chairs to expand into a bigger team. Possibly based on those that have participated in the venue selection. If that were the case, then I think I would naturally be a part of it... But also in this case it makes less sense to be picky and review candidates.