I said it just recently[0] and I'll say it again: those who're big on open source (or at least copyleft) should be jumping hard on the AI opportunity. The core purpose of copyleft is to ensure the freedom of users to do whatever they want with the covered works, chained ad infinitum. Letting AI at said works (and more) now means even more freedom, as now users can trivially (compared to previously) update that code to fit their use case more precisely, or port it to another language, or whatever.
I really can't see a valid reason to be against it, beyond something related to profiting in some way by restricting access, which - I would think - is the antithesis of copyleft/permissively licensed open source.