As he said, they are more public relations. It is not the same people doing both jobs, not in any business I ever worked in.
Job titles more of a way to separate pay grades than they are to distinguish actual duties.
You haven't worked in an office before, have you? A job title also includes job responsibilities. I'm willing to bet that the CM title does not have much to do with customer service short of "don't call the customer an A-Hole". However they do have the right to state an opinion, that is their job. If they just "Grin and bear it" then they would never need to post because their function is to post to get people to post more. Opposing opinions is the BEST way to get a discussion going.