It would be like writing a history of Rome without mentioning Romulus and Remus and the she-wolf...the story is a part of the history. It can be addressed as a legend and debunked. NOT mentioning it at all is effectively to mock the story.
Pointing it out in a Historic context one might be inclined to mention that there is no historic evidence, and that would be a more direct mocking of the story than leaving it unmentioned.
Besides, if the article in National Geographic was about the time period of the building of the great monuments of Egypt the Jewish captivity wasn't even during the same time period.
Maybe they should have mentioned that Elizabeth Tailor played Cleopatra? Was not mentioning that mocking her contributions as an actress?