As I see canon Sherlock as just not interested - not necessarily asexual - his being not interested in the show (Sherlock) works fine for me,

I don't know if it's the nod/wink to slash they put in Sherlock, it's probably just what Martin and Benedict are putting into it,

they are nothing like their onscreen characters in rl, and are friends in rl, its translating. (and that doesn't mean I think that they fancy each other!) It's only us the fans that take it further! ;D