Typing speed? Not sure how much code people here write per hour, but I doubt typing speed is a real issue (the ratio of my staring at the screen thinking versus coding is probably 10:1).
There are at least two people who I'd dub "great hackers" who type essentially, two fingered. One of them suffers from horrible RSI (but, at one point, had the company hire someone to be their hands). The other didn't grow up around computers/type writers (growing up in the 1940s/1950s in Soviet Union), didn't really heavily program until after graduate school and for the first decade mostly programmed by writing cod…
I can't claim he was a great hacker, but he managed to hold his own on the team and even outperformed some. If he can be competent with that level of impairment, I think it's got to be incorrect to claim all great hackers are great typists.