GitHub Copilot is not infringing your copyright

> But the unpleasant side effect of such an extension of copyright would be that all other AI-generated content would henceforth also be protected by copyright.

Proprietary companies are going to lean on copilot and stick "All rights reserved" on the results. Copilot creates this "unpleasant ... extension of copyright".

The author is not in a position to call whether Github infringes anyone's copyright or creates derivative works, the courts will do it perhaps differently in different juristictions.