What I would do: Raise the stakes by putting a CC BY license (or CC BY-NC) on the comics. That way he can clearly spell out the rights associated with the works but require attribution (and retain commercial rights if desired). Then when they start appearing on other sites, all he needs to ask for is attribution and the larger copyright issue goes away.
But his problem right now is that he's not getting attribution while asking for it. Even if he did put it under a CC license, if his content is being reposted with the license and attribution stripped out, and the other party isn't playing nice when being asked nicely, then he's forced into the same situation as he is now, except with a stronger case if he attempts to sue (which he doesn't want to do anyways).
See my comment above. Applying the CC BY license would add legal certainty that attribution is the ONLY thing needed for compliance. He could say, "look I've proven I want you to be able to distribute it with very minimal barriers. please comply with my attribution requirement."
> Raise the stakes by putting a CC BY license (or CC BY-NC) on the comics.
This lowers the stakes. His work is automatically under copyright, and FunnyJunk has zero rights (outside of exceptions like fair use, which clearly isn't the case here) to the content by default.
By raising the stakes, I mean it lowers the things FJ needs to do in order to comply. He could say, look I've ALREADY licensed it for you to use and all you need to to is attribute.
