Ok, fair enough. It's Google's sandbox, they can do what they like.
So let's say ISIS and the Neo-Nazis get their own video hosting services, since there probably aren't enough of either to make that infeasible, and they already have plenty of venues for hosting their own material. Then what?
What problem does removing that content from Google actually solve? The internet detects censorship as damage and routes around it, remember - stopping the propagation of anything people want to publish is impossible by design.
Google removing or otherwise taking steps to suppress this content very obviously (partially) solves the "most important" problem.
And that "most important" problem is Google being accessory or providing platform which is a legal and public relations liability.
Notice who the author of the article is. Not some engineer. Not a public relations person. Nope. It's Kent Walker, General Council. And that tells you a lot about the "why".
So let's say ISIS and the Neo-Nazis get their own video hosting services, since there probably aren't enough of either to make that infeasible, and they already have plenty of venues for hosting their own material. Then what?
What problem does removing that content from Google actually solve? The internet detects censorship as damage and routes around it, remember - stopping the propagation of anything people want to publish is impossible by design.