Having listened to Lowery and Saylor speak about similar topics it does sound like there is something here. To me it seems to be a way of dishing out real world consequences in a digital realm, Proof of work being the core. Danny's point about encryption is well taken but encryption costs nothing so spam is still a problem. Maybe best way to put is the best offence is a good defence. If you make an attack sufficiently expensive that the other party would not even launch it. Then you have won the fight before it even begins. With data and cyber security as critical as they are to modern society its the equivalent of a peaceful American navy securing our data sea lanes. Peace breaks out in cyberspace but no one controls it and everyone can use it.