Personally, I don't believe chat activity is all the relevant to whether you would be a good moderator. I tend to hang out in there most of the day, because I can, but I wouldn't say that there is a lot of moderator focussed activity going on. I feel that not being in chat does not really have an impact on your effectiveness as a moderator, in fact the best moderators would surely spend more time on Serverfault it's self, doing the work that needs to be done, and on Meta where the discussion about the site is going on.
