It’s a technique he uses to get you, the reader, to understand that you aren’t the person who thinks in terms of elan vital.

In one of his essays on quantum phenomena and personal identity he does it with time. He explains something like if you think time in the universe works in the sense of clock time, then you just don’t have a clue about physical reality, so when he gets to his next point it stands in contrast to the straw layman. But his readers are obviously already the sort of people who do know that, because they’re nominally smart, education-enthusiastic western(ised) nerds, even if they understand next to nothing about how this works out in real physical theory.

So the strawman doesn’t just create a favourable contrast for Yudkowsky’s argument, it constructs them as smart and different from lay people - it isn’t a one-shot effect, it builds as he starts small and piles on increasingly esoteric speculations (even if this is the first “mind = blown” blog post they’ve ever read from this weird guy).