Do not forget it was a national hobby in Holland to sell information on (hidden) jews during WW2.

The initial price was 2,50 (Dutch Guilders) at the start of the war, it went up to 40 towards the end.

Dark numbers are said (no without discussion) to be up to 40% of the jews in hiding where sold out.

A third of the Jews that went into hiding were caught and deported, speculation is that these were betrayed but there isn't any solid proof for this, just a lot of circumstantial evidence, and the Germans were pretty rigorous with their house-to-house searches which would span entire neighborhoods. The very best case for this is one built by Ad van Liempt, but it definitely isn't uncontroversial, as is van Liempt himself, who has more than once been labelled 'careless'.

https://nl.wikipedia.org/wiki/Ad_van_Liempt

To portray this as a 'national hobby' is beyond disgusting, a very small fraction (Van Liempt identified a band of about 50 individuals) of the Dutch population ended up collaborating with the Germans on this, the bulk did what they could under exceedingly dangerous circumstances risking their own lives and the lives of their families in order to help others.

Is it? The claims of this book are disputed, but in general I see no issue with stating that those who collaborated with the Nazi regime are responsible for the consequences.

Those who shared information with the Gestapo about where Jews were hiding were knowing accomplices in genocide.

It's easy enough to say "led the gestapo to" or whatever is actually being claimed by the book.

They can be responsible for that, if there is evidence to support it, without being responsible for the arrest. Holding the jewish person at the end of the long chain of actions 'responsible' for the whole situation doesn't really seem that much different from blaming the victims themselves.

If he hadn't been Jewish, does it make a difference?

Yes?

Apparently the theory is that he gave up this family to save his own family, which is a horrific situation to be in. So even if we knew this is what actually happened, and we don't, it's an obvious mitigating circumstance.

No, but it adds insult to injury. Keep in mind that the Germans used all kinds of pressure including the deportation or execution of family members to get people to betray others.

Sure, but how do you hold anyone accountable then? OPs language sounded like a rephrase of "just following orders"

There were extensive legal proceedings post WWII here, the only way people got away with stuff like that is if they fled abroad, even well into the 80's collaborators and other people that betrayed the local population were discovered and tried and convicted.

But this sort of 'posthumous trial by media' is revolting in its own right, especially because the instigators are simply trying to make a buck off the back of Anne Frank (they're not the first and likely won't be the last).