Maybe they need to, after all Pewdiepie did join ISIS...
So what's this really about? It's a terrible business decision, as we saw with Twitter whose stock price fell after they purged various alt-right accounts including the big gay jew. No way is this about making more ad revenue...the only coherent explanation is that it's about censorship and making sure the 'right' sort of information is visible, while inconvenient truths are swept under the financial carpet. Anyone who uses Google+ knows how un-PC posts and accounts are suppressed while causes like BLM are front and centre, and it's no surprise Youtube is basically extending this policy to cut off 'edgy' channels from funding.
(This is why the rules are vague, so they can be arbitrarily enforced against political opponents. btw is it me or do those rules correlate with Sharia law?)
I'm not sure this will work out as intended; after all, Twitter playing games with Pewdiepie's account didn't make him tone it down; rather he showed support (however ironically) for Trump in response.