What do you think?
If it's plagiarism, it's up to the Mods to deal with. I don't even know if Global Mods can do that, or only Admins.
No. That is post plagiarism. Signature design plagiarism is theft that has been dealt with the trust system.
Forum rules apply to signatures as well. We shouldn't use the trust system for either kind of plagiarism unless the staff explicitly refuse to take action and there is an actual risk involved, e.g. the user is promoting a scam.
We have always acted using the trust system, and there is no reason to stop doing so. Forum rules if applicable are an added bonus.
Right, not profitable for any campaign then.