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.
If that is indeed the case again, then this is not good. The user must respond as soon as possible.
Campaigns usually pay for designing their signature. Using the design freely is kind of cheating. Only participants of the campaign should be are allowed to use the design.
FTFY. This has always been the case. Promotional theft of designs, i.e. copy design and make minor adjustments then promote your own service/company, was always dealt swiftly with negative ratings.