I think to be more clear, the point is that there has to be some level of exactness to what is a bannable offense, while giving flexibility to address new or different issues that may not be outlined in the ToS. It shouldnt be to exact or too open ended. As a point, the blanket "Dont be a jerk" is fairly subjective and what defines civility is no different. For some, the mere act of berating someone for being incompetent (regardless of how polite its done) is uncivil. For others, incivility is only a thing when you venture into racial slurs or other like commentary and everything up to that line is fair game. This is why simply saying "Everyone knows how to be civil and and not be a jerk" is not great because everyone has different thresh holds. This gets more complicated because the argument that you need know how to act in a society is misleading - societal norms are not inherently the best. Itd be better to let people behave the way they want, broadly, and give other players the tools and means to choose whom they interact with. It's an understanding that not only are you responsible for what you say, but also in sticking up for yourself. But I digress.
In broader terms, yes SE should more or less outline the exacts of what gets a ban and enforce generally along those lines but also build in flexibility for people not being banned for breaking the ToS but also giving them the ability to ban people for doing things that dont explicitly break the ToS. An example would be using the n-word. Among some people and friends, its used as more of a friendly term. Doesnt matter who agrees if it should be or not, but it is what it is. It would be stupid for SE to straight up ban someone for using the n-word towards a friend theyre hyper familiar with just because the ToS says you cant say it. Even in public chat, a warning or suspension might be necessary but not a straight up ban. For the latter, Arthars situation outlines that. He didnt break any rules directly, but his actions were done as a means to get around the rules and were not innocuous. He wanted to name and shame a particular player and make their life hard but not get in trouble for it, so he went after them off platform to his fan base. SE needs the flexibility to address that issue and were (IMO) in the right to do so.