Post War at that. There’s also apparently a 3rd party hear say claim about van den Bergh. So and so told me they overheard a guard say X sort of thing.
Weighted against a complete lack of evidence that anyone at the Jewish Council had any knowledge of those in hiding or their locations, that it had been disbanded long before. And Franks own statement that he did not know van den Bergh at all.
There’s also that this is a pop book, going through the PR cycle. Not an academic publication. Which is seldom a good sign. A lot of what I’ve seen so far on it, it’s just rooted in a lot of assumptions. If this happened, then that might of happened, and of course so and so would know whats a things.
Along with the AI thing. They don’t seem clear with what they mean by “used AI”, or how, or why that would be compelling as evidence.
I’ve seen comments from academic historians that aren’t just dismissive. But angry. Post War Europe was loaded with these sorts of rumors and accusations, apparently Amsterdam in particular. Claims of Jewish Collaboration, and discussion around the Jewish Councils are still very heated and controversial.