Jefferson had a Koran because we were at war with the Barbary Pirates and he wanted to know the enemy.
The US Marines have immortalized this incident in The Marines’ Hymn (To the Shores of Tripoli) and in the term “Leathernecks”, named after a heavy leather collar that made beheading a bit more difficult.
Taking the oath upon this particular book is tantamount to “Giving Aid and Comfort to the Enemy”, in my humble opinion.
Yes, essentially why the author translated it.
I think what you say is correct, but I’ll go one further. Not only is it aid and comfort, it is a statement to other mooselimbs that he’s using the infidel Jefferson’s own Koran as a statement that now Islam has conquered or is about to conquer this nation that set itself against them under that Koran owner.
One can argue whether that conquered status is actually true, but these days, perception is reality in many circles, as there are few, at least in the media, who recognize that there are absolutes.