Kinda. Since you can self-host the model on a linux machine, there's no meaningful way for them to prevent you from having the trained weights. You can use this to bootstrap other models, or retrain on your own datasets, or fine-tune from the starting point of the currently-working model. What you can't do is be sure what they trained it on

How open is it really though? If you're starting from their weights, do you actually have legal permission to use derived models for commercial purposes? If it turns out that Meta used datasets they didn't have licenses to use in order to generate the model, then you might be in a big heap of mess.

From a legal perspective, yea. If we end up having any legal protection against training AI models, legal liability will be a huge mess for everyone involved. From an engineering perspective, if all you need is the pretrained weights, there's not a clear way Facebook could show up and break your product from a technological perspective, as compared to if the thing is relying on, say, an OpenAI API key rather than a self-hosted Llama instance

I could be wrong but most “model” licenses prohibit the use of the models to improve other models

That's a good point. I expect it is ultimately unenforceable though. I'm describing training a model for myself, not for sale or public consumption.