>> This is what the current terms of service of Copilot say: you as the user are responsible for ensuring you are not breaking anyone's copyright when you accept an auto-completion from Copilot. How you would know that it just spit out someone else's code is unspecified, of course.

This is the key point.

If they were confident that the "generated" code did not violate any copyright or licenses then they would be using Copilot internally or offering indemnity for commercial users of Copilot.

Is Microsoft or Github using Copilot for the proprietary software products they sell? (that is, are they "dog-fooding" Copilot?)

What corporate legal team would be willing to sign off on the use of Copilot for a software product that is sold and distributed?

If the "generated" code is licensed under the GPL and it gets mixed into a proprietary software product then the terms of the GPL have been violated and the proprietary code falls under the GPL.