That’s how double standards work, there often isn’t a clear reason.
The art and audio is somehow seen as more important and something only humans should de in a game than the code and design, you know the actual game portion of the game.
I recently was sent patches for my open source space game[1] that added cascaded shadow mapping[1] and gravitational lensing[3] for black holes, both things that I've wanted for years, but found too difficult to tackle. The patches were made with Claude Opus doing pretty much all the work, guided by a human. The quality of the patches was, in my estimation, pretty damn good. It didn't do weird things, it used the infrastructure already present, it looked like what I wish I could have written. It was clearly not plagiarized in bulk, in as much as it was so well integrated with my existing code, though I imagine all CSM code/shaders and gravitational lensing shaders tend to look pretty similar, or at least do similar things. It was eye-opening to find out that Claude was capable of doing such a thing.
Neither of these changes affect the game play, they are both purely aesthetic in their effects, without introducing anything which might be called "art" in a traditional sense, unless you count crudely modeling the behavior of light in shaders and C code as "art", but at that point the distinction between code and art vanishes. I had previously had a "no-ai" policy in my codebase, just as a kind of over-reaction, and kind of, "if I ban it, then I don't have to think about it" response. But these patches... after studying them, there's just no way I wasn't accepting them.
The art and audio is somehow seen as more important and something only humans should de in a game than the code and design, you know the actual game portion of the game.