The forum rules relating to members and moderators are very clear in my opinion. Members are reminded of them at various times too. Despite that they are often ignored by both members and moderators.
If a member has broken the rules then a moderator should take the appropriate action even if they agree with the points the member is making. Moderators aren't required to be neutral in regard to a case, but they are required to be neutral in regard to the rules.
If a moderator breaks the rules those in charge of the moderators should take the appropriate action also. Perhaps they do, but ordinary members don't know if this happens or not.
The issues become confused when members who have allegedly broken the rules refuse to accept the fact. They accuse the moderator involved of bias. I think that every such accusation should be investigated. The outcome should be communicated to the member and to the moderator so they both know who was right.
If a member makes repeated false accusations against moderators they should be sanctioned.
Of a moderator repeatedly allows bias to influence their actions they should be sanctioned.
I think a few weeks of this would stamp out a lot of the rule breaking and arguing.