There are distinctions between confidences between friends and communication in professional settings. The differences are based on the level of power and consequences based on that information. Boards like these are inherently blurred because they are primarily social. I think the indistinct nature of the context has produced this confusion regarding expectations of communication styles.
I do consider social etiquette to be a strong component of leadership. The way a person communicates about people with a trusted, intimate confidant and professional peers is different. For example, as a teacher it would be unethical for me to express dislike for a student to anyone also dealing with that student because of the power I have in that context. Such feelings would be controlled inside the teacher's head because they are irrelevant to the function of that role. Discussing problems that need resolution w/o any reference to personal feeling is the appropriate, efficient way of addressing student concerns. What are mods? Intimate confidants or professional peers? There is a small level of power involved which suggests some impact on style of communication, but it isn't as significant as in a professional setting. It has a small town management feel to it to some extent. It is a confusing, indistinct setting which has produced this unfortunate event.