IMO a pre-trained model given with the source code used to train/run it is analogous to a company shipping a compiler and a compiled binary without any of the source, which is why I don't think it's "open source" without the training data.
Training data instead source code at all, it's content fed into the ingestion side to train a model. As long as source for ingedting and training a model is available, which it sounds like isn't the case for Meta, that would be open source as best I understand it.
Said a little differently, I would need to be able to review all code used to generate a model and all code used to query the model for it to be OSS. I don't need Meta's training data or their actual model at all, I can train my own with code that I can fully audit and modify if I choose to.
The trained model doesn't need to be open source though, and frankly I'm not sure what the value there is specifically with regards to OSS. I'm not aware of a solution to interpretability problem, even if the model is shared we can't understand what's in it.
Microsoft ships obfuscated code with Windows builds, but that doesn't make it open source.