> Is my understanding of Apple's policy flawed?

Yeah. They're encouraging devs to minimize the amount of data that needs to be backed up, for obvious reasons, but there's nothing forbidding Marco from storing the articles in the Documents folder instead of the cache, and indeed that's probably what he should have been doing all along.

His insistence on keeping them in tmp has caused me to lose a number of articles over the years when I've had to do a clean wipe and the original site has long since disappeared.