I think posting tons is somewhat of a bad qualification for choosing a staffer. It's not like it's awful, but it's quite possible for someone to read tons of threads and be a perfect candidate for moderation, but not post in every single thread they look at.

Anyway, ideally I think they should post a decent amount, contribute to discussions and decisions about members and the future of the site, etc. But I think once you choose someone for that position, you're showing that you really respect their responsibility and decision-making ability, so a lot of that stuff isn't necessary. I think it would be okay if they didn't post a lot if they promoted valid ideas and regularly weighed in on important issues.

After all, that's why we still keep Mullet around!