I would echo the concerns raised here as I have observed people with limited activity becoming moderators on sites in which I participate. I find it odd that on this site where I regard myself as little more than a lurker I have still apparently developed a candidate score of 7. I also find it odd that the reputation threshold for ordinary users to gain access to moderator tools is set at such a high barrier compared to the level for running as moderator.
I would suggest that more credit be given for badges which actually recognise moderating activities and at least some credit is given for participating in the child meta site. Care would need to be taken not to set the bar too high on less active sites. For instance, on the Spanish site, only two people have ever earned the Marshal badgeMarshal badge and only one the Steward badgeSteward badge.