I wonder why that's something worth wondering about.
Maybe they like it? It's a perfectly reasonable systems language, even if it's not my personal favorite. It might be something questionable if they used Fortran or Algol-68, sure.
I think it's a fair question to ask; what particular qualities of D drew them off the beaten path for this kind of task?
Now, I know the answer as a former D acolyte - it's an interesting language with powerful abstractions, albeit hobbled in some ways - but most people don't, so I think it a reasonable question to ask.
