If they have only the rights that their human creators have, then access to them cannot be sold, in the exact same way that I cannot sell you a database that I have collected filled with copyrighted material. The "humans do training too" argument only holds if you imbue LLMs with similar rights to humans.
I am allowed to sell myself (in a very limited capacity) to others for them to exploit my training, even if that training was on protected material, which is a privilege humans should have, but machines should not.
However, because it is an issue with (at least historical) goals of copyright law, the common pattern that is evolving is that AI is not granted copyright of any work it generates, making it a bit of poison pill for some of the egregious ideas of corporate abuse. Not sure if the weights will be considered copyrightable either.