"A man of his type" probably just meant "a mad scientist". The stereotype was as strong as ever at the time (thanks to Einstein and the nuclear-science culture of secrecy), and Turing fit it to a T: he dealt with concepts the average coroner couldn't even start to comprehend (advanced crypto, information theory, Frankenstein-style machinery full of valves and levers, experimental chemistry), he was a loner, socially awkward geek, who somehow didn't really like to hide his homosexual side like a proper Englishman would do (homosexual experiences were much more common at the type for the ruling class, due to boarding schools).