I was actually wondering why this wouldn't just use React for the view. Then it could leverage all of the work going on with React (server-side rendering, possibly rendering from within a Web Worker, etc.)
Given the philosophy leo outlines, I'd guess he's going for something slimmer. This is 3k vs react's 29k. I am curious to know how it's achieving the same thing in so much less code, or rather, what react can do that mithril can't.