I wasn't even aware of this until I read OP's post.  I have signatures blocked, so I don't see any of them and I figured that when members got a signature ban, their sig field would just be blank.  Interesting that Theymos decided to put a message there instead--and I agree with you, it does send a loud & clear message about plagiarism.  Obviously either don't read the rules or don't think they're going to get caught copy/pasting, so maybe this is exactly what we need.

And as far as the hurt feelings resulting from the 'scarlet letter' sig-banned members have to wear, I don't have much sympathy for them.  They're lucky they're still able to post instead of getting a permaban. 

In addition, I haven't heard any teasing or taunting yet and somehow I don't think it's really going to be an issue.  The vast majority of members here are just shitposting and wouldn't even bother to say anything negative about someone's sig message.  And I mean, come on.  This forum is freakin' brutal enough as it is.  If you don't have a thick skin, this isn't the forum for you.