This is not the official word, but just my eerily accurate interpretation of reality:
The “Do not be a jerk rule” is part of the larger “We can revoke your privileges at will any time we want rule.”
You might ask (and indeed, your OP implictly does ask)… Why does this board and many other boards have this rule?
The answer is this. If they listed bannable offenses as being X, Y, and Z. Then some jerk is going to come along and do Q, which the board administrators never thought of, but is certainly worth banning the jerk who did it because Q is just downright offensive (or illegal, or disruptive, or etc…).
However, if they ban someone for doing Q, that jerk will then sue the Board saying, “But Q wasn’t listed as a bannable offense.”
The same thing happens if someone does X, which is listed as a bannable offense. The Board bans the jerk who did X, but now that jerk is taking them to court claiming, “It looks like X to you, but it’s not, and I’m going to get a jury of my peers to prove it.”
By having a ‘bannable at will’ clause in its agreement with people who wish to be Board members, then the Board administrators don’t have to worry about being sued for violating its own membership agreements. When someone does X, Y, or Z or the unexpected Q; then the administration can ban the jerk at will without proving that the jerk broke any specific rule.
Now, you might say to yourself, “That’s all fine and good for a Free Board, but when I pay for a Pay-For Board, I want a membership agreement which will allow me to sue the Board administration if they ban me unfairly.”
Good luck finding one. Almost all Pay-For Boards have a ‘ban at will’ clause to protect their asses from being sued for breaking their own banning procedures.
I can’t speak for this Board’s administration, but I’ll bet all I own that they’re gonna keep their “ban at will” and “don’t be a jerk” policy when it becomes a Pay-For Board. You can complain all you want and demand a membership agreement that will give you hard and fast banning rules, but don’t count on it. If it don’t like the membership agreement, then don’t join.
You can certainly ask they reconsider. Fine. When they say ‘no,’ please don’t whine about it. That’s their business model (and the business model for almost every other Pay-For Board) and if doesn’t work, they’ll have to live with it, and you can gloat when that day comes.
In the meantime, realize that your request (and by “your” I also mean all the ones asking for a banning offense list and procedures) is unusual, and the SD isn’t being unreasonable.
Peace.