No, because fine tuning is basically just a continuation of the same process that the original creators used to produce the weights in the first place, in the same way that modifying source code directly is in traditional open source. You pick up where they left off with new data and train it a little bit (or a lot!) more to adapt it to your use case.
The weights themselves are the computer program. There exists no corresponding source code. The code you're asking for corresponds not to the source code of a traditional program but to the programmers themselves and the processes used to write the code. Demanding the source code and data that produced the weights is equivalent to demanding a detailed engineering log documenting the process of building the library before you'll accept it as open source.
Just because you can't read it doesn't make it not source code. Once you have the weights, you are perfectly capable of modifying them following essentially the same processes the original authors did, which are well known and well documented in plenty of places with or without the actual source code that implements that process.
> Calling these models "open source" is a runaway misuse of the term, and in some cases, a sleigh of hand.
I agree wholeheartedly, but not because of "source". The sleight of hand is getting people to focus on that instead of the really problematic word.
Fine-tuning and LoRAs and toying with the runtime are all directly equivalent to DLL injection[0], trainers[1], and various other techniques used to tweak a compiled binary before or at runtime, including plain taking at the executable with a hex editor. Just because that's all anyone except the model vendor is able to do, doesn't merit calling the models "open source", much like no one would call binary-only software "open source" just because reverse engineering is a thing.
No, the weights are just artifacts. The source is the dataset and the training code (and possibly the training parameters). This isn't fundamentally different from running an advanced solver for a year, to find a way to make your program 100 byes smaller so it can fit on a Tamagochi. The resulting binary is magic, can't be reproduced without spending $$$$ on compute for th solver, but it is not open source. The source code is the bit that (produced the original binary that) went into the optimizer.
Calling these models "open source" is a runaway misuse of the term, and in some cases, a sleigh of hand.
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[0] - https://en.wikipedia.org/wiki/DLL_injection
[1] - https://en.wikipedia.org/wiki/Trainer_(games) - a type of programs popular some 20 years ago, used to cheat at, or mod, single-player games, by keeping track of and directly modifying the memory of the game process. Could be as simple as continuously resetting the ammo counter, or as complex as injecting assembly to add new UI elements.