The law isn't some autistic computer system, "authentication" is a very broad and amorphous term.

Even if that’s correct, Bambu has a right to then press charges on the users, but can’t really complain about the guy simply copying AGPL software to make it work. He’s not the one doing the illegal part.

Bambu clearly didn’t want to press charges on their users, though, so they weaponized the law to try and prevent this, and it’s causing them issues.

In any case, we’re not in some “only the laws matter” reality, we’re also have ethics and morals to consider, in which case Bambu is clearly in the wrong. If they want to secure their servers, they should do it properly rather than using legal threats.