The GP's claim was not that open-weights models aren't understood. It was that NO model was understood.
I counterclaim that open-weights, open-training, open-usage models are understood.
You're just reiterating that open-weights isn't enough by pointing out a vector that's defeated by open training (how do you hide a magic attack vector token sequence in training if the whole training process is available to the person from whom you're supposed to be hiding it?).
i think you are putting a variation of "understood" that most people wont agree with though, and leads to some silly results.
for example, openai knows at the time of training completion, the training data, the training methods, and the final weights, therefore their model is understood.
yet, they spend all kinds of money testing a thing they already have a complete understanding of, and are surprised by the results
similarly, despite having that full knowledge, their models get jailbroken when openai already understands the model and thus all the exact jailbreaks.
similarly, anthropic and openai knew all those math breakthroughs at time of training completion, rather than after executing the model, and yet they held off on publishing the new math and spent a ton on tokens first, rather than just writing out the proofs based on the training data, methods, and model weights directly