Reducing spam isn't just about having a better algorithm (short of strong AI, and even then two people can reasonably come to a disagreement about whether something is spam or not). It helps a lot to have the co-operation of the users. Something YouTube used to have, but doesn't anymore.
You have been arguing that pissing off the user base doesn't matter, but there is a real cost. Fighting your users means things like people not reporting spam anymore, or deliberately misreporting things that aren't spam.
You have zero proof that this all matters to any significant portion of the userbase. And I was arguing that pissing off the small part of the user base that wasn't happy with Google in the first place doesn't matter. And I stand by my argument. The majority wont care and will enjoy seeing relevant comments from their G+ friends under YT videos.
You have been arguing that pissing off the user base doesn't matter, but there is a real cost. Fighting your users means things like people not reporting spam anymore, or deliberately misreporting things that aren't spam.