Somehow this disagrees, unless the people in the story, stole the drink and name and made up their own version of how it came to be? Interesting.

"The Moscow Mule was invented at the Cock’n Bull Restaurant and Pub on Hollywood’s Sunset Strip sometime around 1941."

https://www.top9rated.com/where-did-the-moscow-mule-originate/

Unless Jack Morgan or John Martin ran Guy's?