For those still interested, this has been discussed on Bob Murphy's blog:

http://consultingbyrpm.com/blog/2013/12/a-bit-of-silliness.html

http://consultingbyrpm.com/blog/2013/12/yet-more-on-tyler-cowen-on-bitcoin.html

and here:
http://elidourado.com/blog/tyler-vs-tyler-on-cryptocurrency-network-externalities/