Perhaps because the AI assigned copyright in the files to the author of the library it copied from and the person prompting it told it to look at that library. Without even getting into the comedy AI generated apologia to go with it which makes it look worse rather than better.
From a pragmatic viewpoint as an engineer you assign the IP you create over to the company you work for so plagarism has real world potential to lose you your job at best. There's a difference between taking inspiration from something unrelated "oh this is a neat algorithmic approach to solving this class of problems" to "I need to implement this specific feature and it exists in this library so I'll lift it nearly verbatim".
From a pragmatic viewpoint as an engineer you assign the IP you create over to the company you work for so plagarism has real world potential to lose you your job at best. There's a difference between taking inspiration from something unrelated "oh this is a neat algorithmic approach to solving this class of problems" to "I need to implement this specific feature and it exists in this library so I'll lift it nearly verbatim".