Actually, I tried to implement something like this as an undergrad and I found that the search space was simply intractable and the fitness function too coarse grained (I.e binary). What I really like about this approach is that they do a trace of the program execution as a heuristic to guide the evolutionary strategy. That's awesome.

As a side note, a few months ago I reached out to this team to ask them a few questions. They are super nice.