Flagging as a means of shutting down opinions people disagree with or to target groups they don't like is unfortunately very common. Sometimes even in organized fashion, where a group will urge its members to flag content from someone they oppose. There have also been instances where a group tried to invoke copyright infringement because someone said their name in a video.
It's assumed this is just an issue of manpower, but it's a much thornier problem. There's a point where a video isn't obviously in violation of community standards and at that point, you're asking one of 100,000 different people to make a judgement call. You're bound to get some wrong and the someone will create a whole other post on HN about it.
