This feels somewhat analogous to games like Quake being open-sourced though still needing the user to provide the original game data files.

Yes its "freeware" or any one of the similar terms we've used to refer to free software.

Academia - nowadays source is needed is a lot of conferences, but the datasets, depending on where/how it might have be obtained, just can't be used or not available and the exact results can't be reproduced.

Not sure if the code is required under an open source license, but it's the same issue.

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IMO, source is source and can be used for other datasets. Dataset isn't available, bring your own.

In this case, the source is there. The output is there, and not technically required. What isn't available is the ability to confirm the output comes from that source. That's not required under open source though.

What's disingenuous is the output being called 'open source'.

No, the term is fine, “source” in “open source” refers to source code. A dataset by definition is not source code. Stop changing the meaning of words.

The dataset is likely absolutely jam packed with copyrighted material that cannot be distributed.

Maybe, but it doesn't mean it's not open source.