Should the library where he read books about physics also be liable?
E.g. look at programming - people who don't know how what a compiler is, are making things that I could only make after a few years into my programming journey.
You obviously get the same results in chemistry or nuclear physics or whatever, the models are heavily trained on code in particular, but if there's a chance that we've reduced the ease of committing certain kinds of crime that were previously gate-kept by knowledge, we should know about it.
I bet the professional would be able to sate the kid's curiosity safely without creating excessive risks.
I've come across detailed instructions on how to synthesize sarin gas on the internet. Anyone who follows those instructions will probably die horribly. I still thought it was pretty interesting.