It really is not complicated.
No offense, but it is hard to know the intent of Rule#5, Or how one would stay in the safe zone of such a all encompassing statement. I can see some folks having a problem with it.
You don't need to know the intent of a rule to follow it and as has been pointed out, it's not so much a rule as additional info as a footnote to Rules 1 through 4. But since it seems to be so important to some of you, I'll tell you.
If you violate Rules 1 through 4, you are not promised a warning.
Rule #5: If you behave like a bozo, whether it specifically violates Rules 1 through 4 or not, you may receive a warning, you may not. And what constitutes "behaving like a bozo" is up to staff's judgement. It usually involves general uncivil behavior or constantly having to be warned. If you become high maintenance, you are a candidate. I can tell you that staff is reluctant to swing the axe on any member. A banning will be due to an obvious offense or one agreed on by more than one staff member, if there is a question.
I hope that helps