Are you suggesting these people work for Whatsapp?
You could make the news with that kind of info.
You could make the news with that kind of info.
So the ownership of Facebook is irrelevant in this case.
Now perhaps it is possible to argue if someone hacked into Facebook to steal all data. But I don't think that's the case here.
But the point of ownership of Facebook is moot unless the claim is that somehow all this data was scrapped from the backend (WhatsApp is a messaging app, even claims end to end encryption too).