

This got rejected from Steam in January and the C&D was in March, but in between that Valve updated their Source SDK to add all TF2 source code, so it’s not like they’re completely anti-mod.
As usual, Valve doesn’t communicate with anyone, so who knows what’s going on there.
People are saying the reason is that they used/worked with leaked CS:GO code, which Valve doesn’t like, but the devs deny it.
I don’t think so. They deny it, so who knows. There’s also the exploit allegations, that were mentioned in this thread, but there’s just no source for anything.