That's a really poor response.

When Joyce published his first novel as a nobody, people like you would've said something equally thoughtless about his grammar, followed up by a glib "the writer is no Arthur Conan Doyle."

James Joyce followed proper English when he published his first novel as a nobody. (And his second novel, and third.) He was also a professor of English at the time, so he wasn't really "a nobody" even then. So he may not be the best test case.

His point entirely stands despite your carelessly dismissing one part of it.

Absolutely agree. It is called 'artistic freedom' after all. Right?

Style is not the same as making a mistake.

And who should be the arbitrator of style vs. mistake?

It's easy enough to ask the person that wrote it. Why, do you think answering that is typically difficult or unclear?

And to be clear I mean asking about specific instances, so don't point back at the blog post, which seems to be a case of Amazon making a mistake. All of the hyphens quoted from Moonstruck are grammatically correct.

True, if the process just involves asking the author then I have no issues with that, and it should be easy to resolve.

I do think it is difficult for anyone other than the author to answer that question though. For me, only the "red-head scarf" example would be a mistake, but others in this thread indicated that 3 or 4 of the examples were wrong for them.