The same question was asked when I gave the talk. I'm afraid the only answer is: because I could :-) I thought up a project where it would make some sense to use Elixir and went with it. It's not practical or "real world" project at all!
The point is that the integration Python<->Elixir can be so tight and that there's little overhead when using each language for things it's good at.
I will look it over, and because I favor LFE (Lisp Flavored Erlang) over Elixir, try to do something neat like this. Although, Elixir is growing on me from my initial take on it a year ago.
