You should never use Google's estimate as a real estimate, especially once it gets past 100. There are better ways to move content, like 301 redirects or rel=canonical.
So only firehose agreements get data? What's the impact to general SEO or 3rd parties? Doesn't sound good.
Except don't they have a special deal with Google to use the firehose?
IMO, that's exactly the reason. Before search engines could scrape the data and load the content for free. Now they'll need to reach firehose data agreements.
Take a look at the robots file without the "www" subdomain. Its likely to prevent content duplication/push for only the non "www" url to appear on search engines.