The highest search result I found from Blogger seems to say the same thing:
To simplify custom domain configuration on your blog, Blogger only accepts non-naked domains in our sign-up process. If you try to enter a naked domain in the advanced settings of the Settings | Publishing tab, you will run into an error stating that Blogs may not be hosted at naked domains.But you can use a naked domain! (sort of). No hosting, redirect pages or .htaccess files required. You can achieve the same result by configuring some A records on your naked domain to redirect to Google's server.
To fix this, simply enter the non-naked version of your domain and save your settings.
I knew I saw this somewhere while I was setting up Ferny Blog but it has taken me far too long to find the information in Google's documentation.
But found it I did - Look at the second half of this page