The very lengthy discussion around the concept was fascinating to me as a 23 year old college student who only knew it from one perspective.
This is not copyright as we know it. Copyright protects against copying, not accessing data. You can still compile statistics off data you don't own. The models are like a compressed version of the originals, so compressed you can't retrieve more than a few snippets of original text. Newer model train on filtered synthetic text, which is one step removed from the protected expression in the copyrighted works. Should abstractions be protected by copyright?
Let's say I quote some key parts of a copyrighted book in an way that complies with fair use for a work of mine. In order to find the quoted parts I have to read the whole book first. To read the book first I need to acquire it. If it was simply pirated, wouldn't that technically be the main issue, not the fair use part in their service? I am an absolute layman when it comes to the subject of law and just thinking loudly. It seems to me that admitting using pirated works could be more problematic on itself, regardless of the resulting fair use when it is clear that the whole content had to be consumed / processed to get to the result.
If you liked Tintin and long for more comics of the same kind, I recommend you to try Blake and Mortimer. They're different (e.g. with a more serious and wordy style, hardly any comical gags, but also with more fantastic elements). But they are the closest I know, and in some aspects even better (I personally prefer them although I'm aware it's due to very subjective factors, most people would still rank Tintin higher overall and Blake and Mortimer don't have such a universal acclaim).
The only thing I dislike about the post is the gratuitous rant on AI at the end. It is great news that Tintin joins the public domain. Especially great because it's one of these cases where the owners have been especially abusive, chasing fan efforts done as a labor of love, lest they harm their sales of overpriced merchandising.
Why exactly should be worry about people generating AI images of Tintin? What is the harm done? We know what the original albums are, they will probably be preserved as long as there is human civilization (despite copyright, not thanks to it), and we can freely decide if we also want to read/watch/see derivative works (and which) or not. I just don't see the problem at all.