The entire concept of copyleft and free software depended on copyright: it isn't "take my code and do what you will", it is "here is a very explicit contract that demands you credit my work and even requires you to contribute back in return for my efforts". And like, maybe a world with no copyright at all is better! But that isn't the world we are in: it is no more legal for you to have an AI read my code and then port it into your codebase (which could involve training as an intermediate step or could merely involve the AI searching for it and loading it into its context) than would be for you to directly read my code and port it into your codebase or even for you to utilize a deterministic tool to read my code and port it into your codebase; you only get to do those things if you retain my license on the result and abide by its terms.

FWIW, many of us who do open source would also find that hypothetical world in which the idea of copyright is abolished rather enticing... but you pretending that is this current world whenever you want to steal our code whilst copyright still paints our interests in using and altering the code from companies that have always been in fear of our community and our licenses (Apple, Microsoft, etc.) as theft is not merely a bit shitty... it is kind of evil/cruel.