A moderator should only moderate the discussion to keep it within bounds of civility.
A moderator should not use his power to limit disagreements or restrict expression of facts and views of others that are reasonably related to the subject. That is especially important if a moderator has a business interest on one side or the other of an issue.
On the electrical forum there have been a few people who object to comments by those who are not licensed electricians. On Pumps and Wells there has been an effort to disparage persons and professions and threats to restrict the comments of some who hold points of view and offer facts that may differ from others on CSVs.
Moderators should moderate; they should not attempt to direct or limit legitimate discussion even if they disagree with it.