It's an interesting experiment, but the author's conclusion cannot possibly follow from the results of it.
your conclusion: that the second experiment disproves the theory that thinking outside the box is useful in solving problems, is itself a fallacy.
For example, there have been some theories such as those of Schopenhauer (see his remarks about Genius) and Freud (see his remarks about Sublimation) that propose creativity is something more like a capacity provided by nature rather than one acquired or learned from the environment.
Rather than disproving the myth, in other words, the experiment might instead offer evidence that creativity is an ability that one is born with, or born lacking, hence why information from the environment didn't impact the results at all.
Let’s look a little more closely at these surprising results.