Sure,(and I think your "algorithm" is better than the author's for choosing which langauge to "deep dive" into), but the whole point of a Thought Experiment is to work off a "crazy" (by whatever logic) hypothesis to see what kind of thinking results. "If I were to hitch a ride on a light wave what would I see? ". "If I knew I was going to die exactly a year from now what would I choose to do?" etc. The crazy hypothesis is taken as an artificial focus to spur thinking.
That said, the author seems a bit clueless (and I am not defending him or his logic). I just wouldn't dismiss the idea of a thought experiment so easily. So yes, if you could learn only one langauge which one would you learn? ;-)
(HN generally has better commentary than the article under discussion. This effect is particularly marked when theit is about some dumb submission that for some reason sparks great discussion.
My answer (fwiw) - C or Haskell. My biggest (programming) fear is working with dumb people on dumb projects. In the days of Java and scripting languages like Python or Ruby, either would be used (by and large) only for very unusual/interesting projects. Most of my work today is in converting Machine Learning research into workable code. The language used is is irrelevanmt to my clients, so eithr would work.Side projects would tend to be more interesting with either of these.
C would give me more job opportunities and many nice Open Source projects to jump into than Haskell I guess, but Haskell might be more mindbending (and fun). And it has a great community of very bright and nice people.)