The law states that it works in all cases but the justification only refers to the publisher's confidence that the answer is no, not that a headline can magically change reality. Whether "design is dead" is a lot more nuanced than a simple yes or no

I always saw that "law" as more a critique of the use of such clickbait-y headlines rather than something to be taken seriously.

The answer he gives in the article isn’t no though.

Obviously the writer was mistaken.