If it's not immoral for humans, how can it be for AIs?
Easily. The average human isn't capable of reading the entirety of the source on Github, remembering it in exactness, and offering snippets up to everybody who asks. The AI very much is capable of exactly this.
The human may use other people's code as a guide to how they approached a particular problem, helping them to develop their own solution. Or, yes, copy-paste a bit of code. But they're unlikely to be offering bits of other people's code to anybody else who asks. The AI, on the other hand, won't be using it to learn anything other than how to more effectively offer appropriate solutions for what somebody else is doing.
Now, on the face of it this might not seem like a bad thing as it will be an appropriate suggestion without the human having to go and read loads of code in order to find it. However the problem is that it is presented without context. And whether you like it or not, the terms of the licence are part of that context.
Biting the hand that feeds IT
