The analogy is actually a bit more complex than that: while PoW is asymmetric in the sense that it's highly expensive to produce a PoW but trivially easy to verify it, bullshit is asymmetric in the opposite direction: not only is it trivially easy to produce bullshit, but it's *also* highly expensive to debunk it.
That makes sense. Guess that's why its not practical to secure a blockchain with bullshit.