I would agree, that a writer can be justified in having certain expectations of their audience, culturally or educationally, etc. -- and/or that they may aim their work at a specific audience of whom having those expectations is justified. I think the use of science fiction and audience expectations is a good one.

And I think that the example as presented does imply that the note says McD; I suspect Thing 2 did mean what the above poster assumed, but yeah, that is reading something into the example. I think the rest of the context implies that this is what is meant, but it's ambiguous, definitely.