The question is whether a person is doing the same as Copilot for this particular case, i.e. reading source code to learn.
You have not really given any argument why this is not the case. Or maybe your reference to scale? So only because Copilot has read more code than a human possibly could, that makes it different? But why exactly is reading a bit of code fine w.r.t. copyright, but reading more code suddenly violates copyright?
Note that the reason why Copilot needs more code to learn is just because the learning currently is not as efficient as for humans.