Indeed a typo, thanks.

I've always taken the objection you mentioned as invoking the problem of reliability of the sense (i.e. Cartesian skepticism), not the meaningfulness of truth. In the story, Mark is no Cartesian skeptic (of course, it's hard to tell, because Mark is a terribly confused person)

I think skeptical objections to Bayesian reasoning are like questions about the origin of life directed at evolutionary theory. The criticisms aren't exactly wrong - it's just that the theory targeted by the criticism is not trying to provide an answer on that issue.