Sorry, but it would have been much harder to remove the capstone, than the effort to put it on in the first place. It would have involved a lot of people.
Why would you think Leonardo would travel from Italy to Egypt to remove the capstone, then transport it all the way to Nova Scotia and then return to Italy.
There were plenty of other polymaths, some even in the Middle East that could have done it.
Also why not Archimedes ? Michaelangelo ? or even Isaac Newton ?
Without supporting proof, all you have is the plot of a fictional novel.