This is a bit like saying if you hire a freelancer to do some work then you're the author of that work. I'm not too sure i agree with that.

Kind of interesting.. I would like to point out this seems to be specific for the US.

But also.. In that case, when I commission an artist to paint my portrait, surely I can't claim to be the artist.. But I'm no lawyer.

I'm not sure there is a contractual agreement in GitHub's co-pilot that says: "Any code you write here is commissioned work". But honestly I didn't read the T&C's.

So I think you MAY have debunked my analogy, but not the main reason for the analogy.

How is copilot not the author?

Copilot is software, it can't be the author, just like the OS isn't the author when you copy and paste. Authors have to be humans.

Copy and paste doesn't really write code, just copies it from one place to another. Copilot on the other hand does generate new potentially novel code.