Yeah, I think you're 95% there. Of course, I would probably grant the hypothetical author more than just a few more days of life to consider revising his/her work.
One way we might refashion the question stem is "What's wrong with this advice?"
The advice was:
Hey, successful writers, if you finish a manuscript but decide not to publish it, you should immediately destroy it.
(Ouch. That seems harsh.)
Why?
Because otherwise your heirs might publish your potentially embarrassingly bad work after you die. After all, heirs are often bad judges of the merit of the work.
Okay, makes some sense. Writers naturally want to publish the stuff they're proud of / not publish the stuff they're not proud of.
So how could this advice backfire?
(C) is saying that most writers are overly harsh when reflecting on their recent manuscript. So they might read it, think to themselves "This is garbage", and then, following this advice, destroy the manuscript immediately.
The problem is that the work they just read might actually be very good. So they would be destroying a really good manuscript. It turns out, according to (C), that writers are bad judges of the merit of their
recently completed work, just as heirs might be bad judges of the merit of the writer's remaining letters/manuscripts.
We don't want bad judges making decisions.
(C) is saying that when writers read that same manuscript a month, a year, a decade later ... they revise their initial assessment of their work and think, "This is gold!"
So if these writers followed the advice, they would end up trashing a lot of quality work.
True, it would keep their heirs from publishing potentially bad works. But it would also keep them from publishing potentially good works. That how the advice backfires.
Let me know if you're still unclear.