Comment by HPsquared
This is the right terminology. Model weights are literally compiled binary data; they are the output of an algorithm run on a bunch of source data. That training dataset is the "source" of the model. Training data (or the scripts used to generate it) is human-readable and modifiable, like source code. Binary weights are not.
Just to note though, source copyright extends to its compiled form. There is probably an analogue there for model weights.