I recognise the comments from a thread and I think you shouldn't worry.
There are people who have mental illnesses, then there are people who exhibit behaviours that are clearly not acceptable but who don't have an illness, simply choose to be that way.
I guess the language does not clearly make the definition between the two and I can see why you would be upset, but I don't believe the intention is to say that all people with mental illness behave unacceptably.
I would never use the words loon, nut, bonkers or crazy to describe a person with mental illness, they are not appropriate words. Neither is mental illness something to be ashamed about, I quite openly talk about mine in the effort to make it seem as acceptable as being ill in any other way.
We are in a difficult stage, where the majority of people view mental illness as such, an illness to be treated, but there are still people out there who don't judge it so, and so there is stigma connected to the terms.
I can't really conclude because I am guilty of using the terms, about manipulative unkind people, or terrible behaviour. I guess maybe part of the reason I find the terms inoffensive is because I don't view mental illness as offensive in itself and certainly wouldn't connect those words in particular with it anyway, except in a historical way.
I don't think that you should be paranoid anyway, that particular kind of behaviour is chosen behaviour, they act that way because that's who they are, most mental illness is not chosen behaviour and thus very different. It's a different kind of unstable completely. I mean, my health is very unstable, I get ill loads, but no one has chosen not to be my friend because I get sick, same for mental side of things too.