Mmm. The definition I used is the standard definition of superintelligence, used by EY himself:
> A superintelligence is something that can beat any human, and the entire human civilization, at all the cognitive tasks. [0]
I added the "thinks a quadrillion times faster" part but I think that's fair, if perhaps off by a few orders of magnitude.
All of EY's work has an often unstated assumption that AI will adversarially try to kill us. This is explicitly noted in the replies to the AI ruin post. There are a lot of fiddly details that I'm skipping over, but I stand firm that his argument reduces to "it's functionally impossible to stop something faster and smarter than us that really wants to kill us from killing us once it gains sentience."