I read your blog post and it seems what you have argued makes sense.  It seems like by the letter of the law (U.S. law) bitcoin is not a currency.  You also argued that bitcoin is not an investment contract.

To me it seems like if bitcoin is not a currency, and if it's not security (investment contract), then is bitcoin then a commodity?  Seems like you didn't mention anything about commodities, probably for some unmentioned reason.  In The Good Wife the lawyers also argued that bitcoin was a commodity.

I think bitcoin is like gold.  There is no "issuer".  Work needs to be done to "mine" for bitcoins.  Work needs to be done to "mine" for gold.  There is a limited supply of bitcoins and gold.

The value of gold goes up and down.  The value of bitcoins go up and down.  Some people choose to use gold, bitcoins, or both as an investment.

Surely, gold is not a security, nor is it a currency that is issued by a country.  Since bitcoin is so much like gold I have to conclude that bitcoin is a commodity.