A fat, dumb, happy bureaucrat killed him??? Because said bureaucrat feared for his job? I work for the G, and I can tell you (indeed, anybody on Earth can tell) you that the chances of a big-dog bureaucrat losing his job because his department or agecny or branch disappears is astonishingly close to zero. You don’t know this?
You do realize that your theory (president gets popped because of an “idea”) is a bit loony. Every pres has a million ideas, each and every single one of which will please tens of millions AND displease tens of millions. Why aren’t they all dead by assassination?
....every "explaination" is just a theory(guess), and my guess is as good as any other guess.
...do a simple Google search (Kennedy and US notes), you will find that issuing US Notes was not just an "idea" at the time.