Most of the comments I've seen on HN have been personal opinions or legal questions rather than legal opinions. Copilot may be 100% legal - that doesn't make it 100% ethical (depending on your personal ethics).
I see this kind of fallacy all of the time. People LOVE to smuggle in what (they think) the law says on a moral question, ignoring the fact that 1) legal and moral aren’t the same thing 2) laws change over time 3) laws differ from place to place and 4) when talking about what the law should be, what the law currently says is entirely irrelevant.
The existence of every law begins with something subjective. Just because something isn't illegal doesn't mean it shouldn't be. Just because something is illegal doesn't mean it should be.
https://en.m.wikipedia.org/wiki/Appeal_to_the_law