If it is only Gyrsur, I suggest that you contact him and get this remedied. I have sent him a PM.
He has been on and off trolling the ChipMixer signature campaign thread for a very long time, I'm not even sure if it was because he's rejected from the campaign or something else.
Afaik these signatures are not copy-righted and publicly available
Almost everything is copyrighted, but the thing that gets you banned would be for plagiarism.