Obviously I can't speak for these guys, but if I were designing it the fact that Go uses a garbage collector is a pretty strong minus. I like GC'd languages for a lot of tasks, but if I care about performance to the extent that they need to with BIND, I'm not going near it.
Interestingly, they actually wanted a garbage collector:
"The language had to address most of the problems with C.
Ideally this meant something with good string handling, garbage collection, exceptions, and that was object oriented."
Yeah, I saw that, and my WTF sensor lit up. DNS isn't trivial, but it seems like a sufficiently well-explored problem that memory lifecycles should be pretty well-understood.
