Under US copyright law, I believe they are able to train on any open source projects regardless. Some open source projects may be for non-commercial use, in which case copying them exactly could be a violation, but using it to make something similar is allowed. Note that whether an AI is doing it under someone’s instructions doesn’t make a difference, as the copyright law predates AI. There isn’t a way to stop AI scraping other than closed source or legal reform.
Racket is indeed a Lisp and therefore, is said to retain its potent psychedelic effects, but I didn’t stick with it long enough to verify it. If you have some experience, Common Lisp could be better depending on what you want to do.
I think most people use whatever language allows them to best accomplish their goals and, if that changes, switch language.