How would you know if said people are your enemies? You wouldn't unless directly affected by them in some way. As a Neutral you're supposed to uphold balance between Good and Evil and when you simply just say, "Sorry but you're a Demon and even though there are 14 other Goods online and there's just you on that, you're my enemy, just saying." That isn't a good RP reason in my book whether you're in that Cabal or not. Not only is that Demon going to have all of those Goods on his ***, he just had a Neutral tell him he's going to try and kill him and unless that Demon is VERY good at PK, he's probably going to get jumped on all ends.
That guy can't be Neutral because for all you know he goes home and butchers children in his basement, or maybe he's a fellow follower of Purity. You never set any strict basis for it. Judging by that one situation, he's still a Ninja or a Thief who just blackjacked/strangled the guy to get his beer and leave. If by the basis you say he's doing it out of neutrality because he's not doing it for the clerk or the store or to punish the thief, that leads me to believe he's a follower of Greed because he's doing it for himself more than anything.
Now lets say that if IG the Watchers saw character A beating the crap out of everything in the forest that wasn't harming it but was rather protecting it to save it, whilst leaving the Fire Giant Loggers alone to cut it down and then when they were finally able to harm them, so said Watcher kills character A, that would be justified as they themselves are unnatural and thus deforesting nature and killing it off. Now if Watcher sees Character B who he's never seen before and he just so happens to be a Lich but he's killing off a bunch of other unnatural beings (leveling or just a distraction) and the Watcher kills the Lich without a word other than the person is a Lich, I find it very hard to believe that's a Neutral RP whether that's the Cabal or not.
So my stance still stands, as the mugger situation can happen every day, where as it doesn't show signs of his alignment of any which way. I as a person find myself a Neutral Neutral because although I am a nice person IRL, that doesn't mean I'm Good. I don't go out of my way to help people unless I know I can do it without harming myself (neutral mentality), I don't go out of my way to make people's lives a living hell (neutral mentality) and if it came right down to it if I had to kill someone to save my own life in self defense I'd do it (again neutral mentality).
Granted in this game we don't have the obligation to show our back story to everyone we encounter because we'd be explaining ourselves for a LONG time. However, I've seen more Watchers take advantage of those Qraces whom are already low on health from having fought someone or something recently to their advantage which to me is clearly an Evil thing to do. Now if they were to kill said people and never full loot or loot at all that would be another story but back in my day that was rarely ever the exception.
I've never played a Crusader myself, but there are things they do that I would lean towards putting them on the unnatural selection list as well. Some people would probably argue that point, but that's another matter entirely.