Presumably, any search engine that works passably well will not show you snuff films if you type in a search for something entirely different. The only people who see snuff films will be the ones looking for them.
Child porn shouldn't be on the internet because it is illegal, and if it's not on the internet, it won't come up in search. If it does come up in search, that makes it all the easier to report to the police.
Freedom comes at a price and I believe, while I'd never support such results, the scenario that includes unwanted/illegal results is still better for the pursuit of taking power and control of freedom of speech from big corps and governments in the long run.
Child porn shouldn't be on the internet because it is illegal, and if it's not on the internet, it won't come up in search. If it does come up in search, that makes it all the easier to report to the police.