Well, the publicly visible side of work does not seem to refer to specifically this, hence it is not so specified.

With regards to your idea, if you have to make that sort of preference function to really motivate the AI in sufficiently general manner that it may just be hell bent on killing everyone, I think the 'risk' is very far fetched exactly per my suspicion that viable super-intelligent UFAI is much too hard to worry about it (while all sorts of AIs that work on well specified mathematical problems would be much much simpler) . If it is the only way to motivate AI that is effective over evolution from seed to super-intelligence, then the only people who are working on something like UFAI are the FAI crowd. Keep in mind that if I want to cure cancer via the 'software tools' route and I am not signed up for cryonics then I'll just go for the simplest solution that works, which will be some sort of automated reasoning over formal systems (not over real world states). Especially as the general AI would require the technologies from the former anyway.