Also temporarily assuming his premise, I disagree with your conclusion that this article itself becomes a waste of time: if he convinces a couple people to work on those things he finds important by way of having written and published this article then it may be more beneficial by the stated metric of doing good for the world than directly working on those important problems. I'd instead try to question the value of the post (again, assuming the premise, so in the eyes of the author) by asking this question: "if someone actually finds Yo worthwhile enough of their time to work on, maybe they aren't the kind of person who would actually come up with useful solutions to actually important problems anyway". Then again, the cost of writing this article is so low that even if the potential reward has very low probability, it has sufficient value (the productive output of another individual working on important problems) that it is probably still worthwhile (again, if you agree with the basic premise).