They just have to learn how to ignore does type of replies or make use of the ignore button if they noticed same reply from a particular user and they feel offended by those comments. You can't stop people from acting childish, Irrespective of whether you're wearing a signature, not wearing one or wearing the sig banned message, if trolls or whatever they call themselves wants to attack you they'll.
The sig banned message is passing a loud message to who ever sees it. You commit plagiarism, you get punished so I don't support the idea of removing it.
Then we will not know who really wants to keep posting without getting paid and who doesn't, since the lack of motivation to post while wearing that signature is understandable. So you can't have mods stating how people became inactive due not getting paid. This would be the case if you had a neutral (blank) signature.