I disagree with this in so many ways; nearly all the excellent coders/hackers I know are heavily biased towards certain languages and frameworks. They have pet projects, are idealistic and often fussy about what they work with.
To hire a great hacker you need to have a problem they WANT to work on: something that hits right in their area of interest. And then you need to give them the freedom to do it in whatever way they want (cause they know best).