You are treating humans as reasonable actors. They very often are not. On easy to access platforms like github you can have humans just working as intermediaries between LLM and the github. Not actually checking or understanding what they put in a pull request. Banning these people outright with clear rules is much faster and easier than trying to argue with them.

Linux is somewhat harder to contribute to and they already have sufficient barriers in place so they can rely on more reasonable human actors.