I do not understand it, because I think Meta is for forum-related issues. This one relates to forum issues, in my opinion.
Signature rules were decided by the respective campaign managers so this has nothing to do with forum.
You can bring this topic into Reputation and get the discussion going about the issue.
I don't think there are much bitcoin paying signature campaigns accepts copper members of they don't have atleast 10 merits but on bounties everything accepted because all they want exposure.