>I think my arms dealer provides a much clearer example of facts removed from tech where people in HN are understandably defensive.

guns are much simpler situation, and this is why it doesn't make the situation clearer. Imagine if that specific gun dealer could look into the brain of a buyer. Would you hold him accountable for not checking the Parkland shooter's brain?

>the law does create liability if the seller knew or should have known the buyer intended to use the good/service in the commission of a crime.

Is SaaS company "should have known" what is in the data it is SaaS-ing? We know that the answer is "yes" for banks according to the explicitly written money laundering, etc. laws. There arent such explicit laws for SaaS, for Facebook, etc. Is Facebook liable if somebody uses it organize a crime like say a bank robbery or an unpermitted protest?