Did he register silkroadmarket after the known existence of silk road? If so it could just be a domain squatting attempt for marketing purposes (e.g. "thinking of using silkroad? come first to mtgox, the best place to convert your $ to Btc".)
silkroadmarket.org was registered on February 28, 2011 [1]. According to a forum post [2], Silk Road was launched around three weeks before March 1, 2011.
