Its not IMHO.
Starting from that, the machine in the room wasn't clean - it ate all the source codes with all the licenses, now produced washed out codes without licenses - but it doesn't have any right to strip them even asked for, neither results of that could become somehow legal - the codes used, even if remixed, are still under the same license as before, even if label about that was "lost" in the process.
And it may happen to be easy to prove - that a room with washing machine for dirty stuff there wasn't clean:
"Finetuning Activates Verbatim Recall of Copyrighted Books in LLMs" - https://arxiv.org/abs/2603.20957
(And.. Be safe. Keep your copyrighted code - or music - out of AI reach - or you may lose any rights to them, even could be sued - with your price grabbed by machines remixing them freely so far ;)
Works produced by AI can't "loose" copyrights of used original copyrighted works, regardless of remixing - then only if no such works were used the results produced by AI can be copyrights free.
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AI machines that doesn't trace legal rights but strip of them - what indeed is a robbery - shall be forbidden as criminal until that would be fixed, with respect to the law and original creators.