You make the start of a good point, but miss most of it.
You can absolutely have open source machine code.
The issue is and always has been that you need to have access to the same level of abstraction as the people writing the source code. The GPL specifically bans transpilers as a way to get around this.
In ML there is _no_ level of abstraction other than the raw weights. Everything else is support machinery no different to an compiler, and os, or a physical computer to run the code on.
Linux isn't closed source because they don't ship a C compiler with their code. Why should llama models be any different?