In fact the whole premise of the article (comparing moderation policy differences between different subreddits) - would suggest they totally understand that reddit moderators aren't all pulled from one homogeneous pool of employees.
I think the "site wide" bit was actually brought up by the moderator - referring to the fact that the /r/moviedetails moderation checks your full post history across all of reddit (not just your behavior on /r/moviedetails) and bans you from their subreddit based on that.