No no, see the GNU GPL is copyleft:
The licenses in the GPL series are all copyleft licenses, which means that any derivative work must be distributed under the same or equivalent license terms.
https://en.wikipedia.org/wiki/GNU_General_Public_License
So if (stressing the if) output from an AI that was trained on GPL code is considered a derivative work, then it must also be licensed as GNU GPL. That makes it open source, but not unlicensed.
GNU GPL is intentionally insidious this way, it prevents corporate profiteering from GPL projects because any derivative work must use the same license.
The question is whether a court decision would uphold that AI generated code based on GPL code training counts as a derivative work. This decision regarding generated art seems like it might set a precedent for that.
I suspect the timing of this has a lot to do with the Supreme Court’s refusal to hear the appeal regarding copyright for AI-generated visual art, which effectively upholds the Copyright Office’s determination that copyright only applies to human-created works.
If Disney (or any other prospective customer) can’t claim copyright over anything a generative model might produce, then it has no commercial value.