This is like saying, hey, a regular binary executable is fine because I can edit it with hexl-mode.
Or should I say, it held water until few days ago.
Personally though, I never bought it. Saying that weights are the "preferred form of the work for making modifications to it" because a) approximately no one can afford to start with the training data, and b) fine-tuning and training LoRAs are cheap enough, is basically like saying binary blobs are "open source" as long as they provide an API (or ABI) for other programs to use. By this line of reasoning, NVIDIA GPU stack and Broadcom chipset firmware would qualify as open source, too.
I don't build my browser, it's too expensive, but the cost of building has nothing to say with how open the access to things. It'd be cool if the community could fork the project, propose changes and maybe crowdfund a training/build run to experiment.
But probably it is impossible for them to release the training data, as they have probably not made it all reproducible, but live ingested the data, and the data has since then chanced in many places. So the code to live ingest the data becomes the actual source, I guess.