In my view, it's knowledge work. Sure, it's knowledge work that almost anyone can be trained to do, but there's a skill set required.
For example, moderators need to make judgment calls that distinguish between offensive uses and artistic/journalistic/parody uses. There are many cultures and in-groups on Earth, which makes this harder than it might seem at first blush. Not all nudity is obscenity, not all hate speech is blatant.
In these cases I'm not sure it really matters. Over-moderation is going to win overall and I don't think moderators are going to get into that much trouble for being slightly over-zealous. I could be wrong but I feel like after a week of being on the job you'd get the hang of it.
Some of the decisions taken by the moderators are then reviewed by a "super"-moderator and the match between the two decisions (including the rule chosen) is used as a performance indicator, which has to be above 90% to avoid troubles.