You're right, unrealistic is not the right way to describe it. I don't doubt that quite a few people are able to make a couple thousand off adsense and 150,000 pageviews or less per month.

However, the article is saying it is incredibly easy to do this. On that point I disagree. I think if you spend a lot of time working on finding the right niche and developing the site that you can definitely pull it off, but I don't think it's easy. And, as someone else pointed out there are a lot more interesting ways to make $2000/mo building a niche web app.