Update (later today): Blogger appears to have deferred the "no porn" policy and will instead focus on enforcing its rules against monetizing porn (introduced in June 2013). The posting is by Jessica from the Blogger Team. Check the link from the Feb. 24 posting. PC Mag has a whimsical account here, which Webroot tweeted today. The account didn't take the underlying problems seriously.
Update (March 4): Blogger's updated policy statement is here. Note that adult interstitials may be turned on by Blogger, and blogs that "defy" could be removed. Again,, the term "porn content" doesn't cover the scope of the problem.