The interesting part of the product we’re taking about (that is, the equivalent of the executable binary of an ordinary software product) is the weights. The “source” is not sufficient to “recompile” the product (i.e., recreate the weights). Therefore, while the source you got is open, you didn’t get all the source to the thing that was supposedly “open source”.

It’s like if I said I open-sourced the Matrix trilogy and only gave you the DVD image and the source to the DVD decoder.

(Edit: Sorry, I replied to the wrong comment. I’m talking primarily about the typical sort of release we see, not this one which is a lot closer to actually open.)