But if open weights are banned the companies and the governments still have them and can engage in whatever manipulation etc., that they want.
Furthermore, it means that these entities can listen to everything being sent into the models.
If the model weights and training data are not published you can't even try to determine whether the model is designed to manipulate you, because you don't even have a fixed object to look at. If you find something weird about the model and start probing, they can just change the model to be less obvious.
This kind of thing: government or commercial manipulation of models is one of the main problems, and the ability to probe, fine-tune and and modify the models are what allows ordinary people to make them do what they want; and this is a free speech issue. LLMs are going to be critical for journalism, to sift through data, to sift through other people's news and characterising it objectively, etc., and that requires absolute control of the model, which makes access to the weights absolutely necessary.
If there are restrictions on LLMs, then OpenAI, the diverse governments, the CIA, etc. must be subject to as severe restrictions as I am.