I've seen estimations that verbatim copies of training code constitute around 0.1% of the code produced by the Copilot. It would be relatively straight-forward to implement a verification step that would remove this code. I would be surprised if it hasn't been done already.
With verbatim code copies out of the way, I don't see any basis to consider code produced by Copilot copyrighted. So unless you have some problem with the fact that portions of your code will be public domain, I don't see any reason not to use it.
And one more thought. The author gives an example of using Copilot to list prime numbers. That's not a good use for it. Copilot and similar systems are primarily useful for writing boring boilerplate code, saving your time for more involved parts.
With verbatim code copies out of the way, I don't see any basis to consider code produced by Copilot copyrighted. So unless you have some problem with the fact that portions of your code will be public domain, I don't see any reason not to use it.
And one more thought. The author gives an example of using Copilot to list prime numbers. That's not a good use for it. Copilot and similar systems are primarily useful for writing boring boilerplate code, saving your time for more involved parts.