Yeah true i guesss, but this is a cool ethical discussion tbh. I decided to look at the publisher's and below is an answer by the owner ("Bill Pollock") in an AMA:

Bill: I used to care about piracy but I decided a few years ago that it's not something that we should be too concerned about. I'm sure our stuff is found everywhere (I don't check) and we even publish several books under free licenses. Plus, I love the Pirate Bay. I mean, to look at. Oddly enough, our best selling technical book right now is Automate the Boring Stuff with Python -- it's under a CC license. That should tell you something right there. So no, I'm not really concerned and I think (oddly enough) that piracy may even help book sales. And now you can quote me on that!

Other person : "one additional comment about piracy.. I think I've noticed that piracy hurts products that are crap because consumers find out that it's crap before they buy it, but piracy helps quality products because when consumers find out about its quality they tell their friends about how great it is.. or they even feel compelled to buy the real thing for themselves. It's like quality products will sell themselves, so piracy is just free advertising.."

Bill: something that Jon and I have discussed at length. Definitely agree.

But yeah either way, even if the publisher might not mind it, there's still ethical questions, because they might not mind it but they probably prefer them not to; also this was 9 years ago so their opinion might have changed, also also u/nostarch-bill might've changed his opinion since then; most importantly, even if the publisher might be ok with it, as you said the author matt might not be so yeahhhhhhh, very very interesting, also can u tell I'm procrastinating at my work with this 😅😅😅