As you designed it, I think it adds too much visual clutter for what it's worth - only a minority would make any meaningful use of this. Most would leave it on the default, which is likely to be the most restrictive option (anything more permissive as the default is likely to cause more problems than it solves).

Something to keep in mind is that PJ is not OpenGameArt, it's not a place to find art you can use. If you find art on PJ you like, the polite thing is to see about commissioning the artist for new art for you, not to ask if you can use art they already made - some artists even find the latter approach insulting. Your feature suggestion will allow artists to pre-empt these kinds of messages, which is great - as long as artists are given sufficient control over it, and are able to become informed about licensing in general. That latter part is the hard part - most have no reason to care about it.

If this option is added, the default should probably be the Berne Convention (which would probably display nothing at all). If an artist wants to go out of their way to add a more permissive licence, I'm all for PJ giving them the option, as long as the licence information is a small link that is not distracting in its appearance and its location. The mockup is distracting in both ways.

I’m likely in the minority here, but I personally don’t give a damn about people using my art (if they actually do) for their own projects or whatever. Everything is a remix and all that jazz. (And I personally believe in growing the public domain rather than shrinking it.) That said: yeah, someone can just toss in a link to a CC license in the description of a piece if they really want to add one. We don’t need to add a whole new setting for something that can already be done if an artist feels the need to do so.

Well, it all depends on the way to see, it if they believe it is not necessary to add this feature, then I will not say nothing more about the suggestion.