This isn't something that got passed down like a children's game of "telephone"; the outlandish details are present in the original contemporaneous accounts and

This isn't something that got passed down like a children's game of "telephone"; the outlandish details are present in the original contemporaneous accounts and we have copies of them (digitized even! [1]). So, if it was made up, it was at least made up at the time. However, the person making the claim is Pierre-François Percy [2], chief surgeon of Napoleon's Grande Armée and a member of the Académie des sciences and, later, honorary member of the Académie Royale de Médecine. Inventing a case like this would be wildly out of character. Reflexively dismissing every story from the past is just as fallacious as believing every detail. [1] https://books.google.com/books?id=4e0EAAAAQAAJ https://books.google.com/books?id=4e0EAAAAQAAJ [2] https://en.wikipedia.org/wiki/Pierre-Fran%C3%A7ois_Percy https://en.wikipedia.org/wiki/Pierre-Fran%C3%A7ois_Percy