You do know the difference between undersea methane and permafrost, don't you?  A brief look tells me Ruppel investigates the former, not permafrost. 

 The Wiki article shows many post 2011 warnings about large and increasing, and terrifying,  releases from permafrost.  I await your link to  a 2016 article by Ruppel on permafrost, which was the focus of my first comment.