Sherlock Holmes Gay? Sequel Threatened

Guy Ritchie's Sherlock Holmes is still at the top of the box office charts.  People are loving Robert Downey Jr as Holmes and Jude Law as Watson, but there might not be a sequel if Holmes loves Watson.  Could Holmes be gay?
 
According to Total Film, in an interview with David Lettermen, Robert Downey Jr wondered if Holmes was actually a "very butch homosexual."  This comment did not sit well with Andrea Plunket, holder of the U.S. copyright to Sherlock Holmes.

“I hope this is just an example of Mr Downey's black sense of humour," she says. "It would be drastic, but I would withdraw permission for more films to be made if they feel that is a theme they wish to bring out in the future.

"I am not hostile to homosexuals, but I am to anyone who is not true to the spirit of the books.”

Would it make a difference if Holmes were portrayed as a homosexual?  Is this untrue to the "spirit of the books"?  If it is, then is Wildstorm's current Victorian Undead comic, in which Holmes fights zombies, also untrue to his original spirit?
 
Sherlock Holmes was never involved with anyone romantically in the original stories, and even the new movie eschewed straight-up romance.  Maybe Sherlock's sexual orientation will have to remain an unsolved mystery.