Masternodes are a digital asset which promise a return/dividend, thus they are investment instruments.
Duffield's lawyer must know this, but either thinks THE DARKCOIN FOUNDATION INC. can get away with it, or is helping some TLA build a honeypot in exchange for immunity.
Except in DASH's case the blockchain pays the masternodes for the work they are doing. Just like it pays the miners for the work they are doing.
You're not promised any return or dividends for buying the coin.