The broader point anyway is that resources like search engines (which are really just massive libraries) ought to be relatively free from bias, or blocking resources on some political grounds. I don't want holocaust denial to be widely-publicised exactly, but on the other hand it is not a crime in this country, at least, to be wrong, or to research the wrong things. Freedom of speech seems to imply the freedom to say something that's "wrong" in that sense.
So no, I don't think that Google should block sites just because we don't like what they say. That risks politicising what's available. Never mind that it doesn't solve the problem anyway. The sites still exist, there are other ways to find them, and all you do is push the thing underground rather than keep it in the open where it can be exposed to criticism, ridicule and rejection openly if appropriate. There's also the more serious problem of -- well, I'm not a fan of the slippery slope argument, but it's still true that it would set a dangerous precedent. What if Google didn't stop with blocking this stuff, and started blocking or censoring sites from its search algorithms based on a wider agenda? No-one should tolerate that, whether or not it supports their own views.
(Criminal activity, of course, is another matter entirely.)