Got it, that makes sense. I still wouldn't expect them to have to publicly share the data itself, but if you can't take the code they share and run it against your own data to build a model that wouldn't be open source in my understanding of it.
Data is the source code here, though. Training code is effectively a build script. Data that goes into training a model does not function like assets in videogames; you can't swap out the training dataset after release and get substantially the same thing. If anything, you can imagine the weights themselves are the asset - and even if the vendor is granting most users a license to copy and modify it (unlike with videogames), the asset itself isn't open source.
So, the only bit that's actually open-sourced in these models is the inference code. But that's a trivial part that people can procure equivalents of elsewhere or reproduce from published papers. In this sense, even if you think calling the models "open source" is correct, it doesn't really mean much, because the only parts that matter are not open sourced.
Compare/contrast:
DOOM-the-engine is open source (https://github.com/id-Software/DOOM), even though DOOM-the-asset-and-scenario-data is not. While you need a copy of DOOM-the-asset-and-scenario-data to "use DOOM to run DOOM", you are free to build other games using DOOM-the-engine.
I think no one would claim that “Doom” is open source though, if that’s the situation.
That's what op is saying, the engine is GPLv2, but the assets are copyrighted. There's Freedoom though and it's pretty good [0].
They only give you a blob of data you can run.