Not at all. That essay simply says that non-deterministic algorithms don't perform better than deterministic ones (for some meanings of 'non-deterministic algorithms'). But the claim that needs to be explained is how determinism helps to prevent "making truly spectacular mistakes".
Right. No doubt he is thinking he doesn't want a cosmic ray hitting his friendly algorithm, and turning it into an unfriendly one. That means robustness - or error detection and correction. Determinism seems to be a reasonable approach to this which makes proving things about the results about as easy as possible.
John Baez's This Week's Finds (Week 311) [Part 1; added for convenience following Nancy Lebovitz's comment]
John Baez's This Week's Finds (Week 312)
John Baez's This Week's Finds (Week 313)
I really like Eliezer's response to John Baez's last question in Week 313 about environmentalism vs. AI risks. I think it satisfactorily deflects much of the concern that I had when I wrote The Importance of Self-Doubt.
Eliezer says
This is true as stated but ignores an important issue which is there is feedback between more mundane current events and the eventual potential extinction of the humane race. For example, the United States' involvement in Libya has a (small) influence on existential risk (I don't have an opinion as to what sort). Any impact on human society impact due to global warming has some influence on existential risk.
Eliezer's points about comparative advantage and of existential risk in principle dominating all other considerations are valid, important, and well-made, but passing from principle to practice is very murky in the complex human world that we live in.
Note also the points that I make in Friendly AI Research and Taskification.