That would be only relevant if Kaj had said "I expect to save the world" instead of "Ideally, I'd like to save the world". I read the latter as specifying something like "all existential risks are averted and the world gets much more awesome" as an optimization target, not as something that he wants to (let alone expects to be able to) do completely and singlehandedly. And as an optimization target, it makes good sense. Why aim for imperfection? The target is the measure of utility, not a proposed action or plan on its own. (Possibly relevant: Trying to Try.)

(One thing I see about that paragraph that could be legitimately disputed is the jump from specifying the optimization target to "One way to do that involves contributing academic research, which raises the question of what's the most effective way of doing that" without establishing that academic research is itself the best way (or at least a good way) for a very smart person to optimize the aforementioned goal. That itself would be an interesting discussion, but I think in this post it is taken as an assumption. (See also this comment.))