Might some truths be incontrovertible beyond business reasons?

Curating IS their business. When you type in "public key pinning", for example, google understands that you want to learn about public key pinning and so it curates OUT results about kim kardashian for example and instead shows you factual truths about public key pinning. Why should the holocaust be different?

AGAIN, google's goal is to organise all knowledge and that's exactly what it's doing. That holocaust denial is a thing is also knowledge, and so you can find it by typing "holocaust denial".