The problem with using the report function to report a problem with a moderator is that the report function just sends a message to...all of the moderators. Since we're all more or less equal to each other—I'm marked as "administrator" because I have access to a few more buttons than the others, but I'm not anyone's "boss" or anything—we really don't have the authority to sanction each other, unless we all feel like someone unquestionably screwed up, to the point we unanimously agree someone shouldn't be a moderator anymore.
If you have a problem with a moderator, I would suggest PMing or emailing Alex. As site owner he has more authority to decide what to do about a moderator than anyone else does.