He's a "modern" Sherlock, done in the current style of writing that is popular with the current wave of British writers: has no real interest in other people. A classic Introfvert. Amoral, uncaring except for selfish motives (like solving a puzzle) (very strong Fi and weak Fe), very strong Sensor observation (Se), only interested in HIS theories (N), very Judgemental. INTJ.
INTJs go well with the common world. They work within the system, but are highly offensive to others. It makes TV dramas very dramatic, without having to actually write intelligent dialogue. Effectively, taking the types of behaviour you see in cheap and very profitable productions like Big Brother, and transplanting them into dramas, to make the same huge profits, for almost as cheap.
Also, by keeping them relatively amoral, and generally offensive, but still making them play by the rules somewhat, it plays to atheist and anarchist sympathies that want their heroes to be as scathing as them, and to religious and conservative sympathies, by working within the system.
Sherlock was designed to be syndicated to the American market, like Torchwood was. The Beeb was going to show it in America. But it turns out that one of the American studios are going to make their own version, called "Elementary". This really annoyed the BEEB, because they had been expecting all those profits, because they deliberately designed the programme to accommodate the American market, by leaving out a lot of the British satire that Americans probably wouldn't understand, or making it obvious using S-type demonstrations, and by trying to appeal to both American atheists and American Xians.
To put the final nail in the coffin, the creator of the new BBC series "Sherlock", Stephen Moffat, explains what he wanted the character of Sherlock to be
Sherlock Holmes is a human that longs to be a god,
A classic INTJ.
Even the version of Sherlock with Jeremy Brett comes across like a smart INTJ.
The original concept of Sherlock, was supposed to be an INTP. The most obvious INTP character I can think of, that is on TV, is Adrian Monk. But as you can see, most detectives are not like him at all, because the audience can only sympathise with him, while TV people are hoping to get people to identify with detectives, as that gives them more incentive to watch, on an emotional basis, which is much more of a hook for getting regular viewers, than a purely intellectual character. So TV has gravitated to dramatic action heroes, and that really doesn't fit INTP well at all, and fits the INTJ character much more readily. The same is true of other current British SF&F programmes. They are geared towards the INTJ-ENFP model, because they have great ambitions, and fulfil them in TV, which then in turn satisfies the millions of Brits who are over-educated and under-skilled, and feel that they would also achieve greatness, if only life would give them a chance, by ignoring their lack of application.