Yeah, I know the real reason for what I'm about to say is probably Americanisms, but I'm going to say it anyway 'cause random speculation is fun \o/.
So, Okiya says he's a Sherlockian, but when SH was set most people were referred to by their last names meaning that most people called him 'Holmes', not 'Sherlock'. So, as he said 'Sherlockian', not 'Holmesian' he's obviously a fan of BBC's Sherlock *nods*