Imagine if every new piece of software your wrote had to be tested for legality because you don't know that it's explicitly legal. Oh there aren't laws for this new thing, so I guess you should challenge yourself all the way to the supreme court?
I get the author not liking Copilot, but I don't see that GitHub/Microsoft have any kind of obligation to figure this out just because they're GitHub/Microsoft.
If I as an individual had this obligation placed upon me I'd just never write any more code.
Ultimately I think, like open source, Copilot and the tools that will follow advance human progress in novel ways. Software getting easier to make is a good thing. If you don't like this particular implementation of something helpful, feel free to start an open source alternative without challenging yourself in the supreme court.