It's not about that at all. I'm more familiar with Erlang than C, and the git source is a twisty jungle of advanced C code. I could have patched git-daemon, but to have a project that I can easily understand, maintain, and improve, I chose to write my own in Erlang. My tests show the Erlang and C git servers to be very similar in performance, so that's not a concern. And I can guarantee that egitd has
far fewer lines of code!
I don't choose languages because they're cool or trendy. I choose them because they make it easier to Get Things Done. And for a startup, that's an unmistakable benefit.