Two points are worth mentioning. First, in light of influencing the Federal government, it makes no sense to kidnap or kill Lincoln and other U.S. political leaders in April 1865. Second, regarding Mosby's involvement, being the nearest operational Confederate command, his part makes sense. However, it makes no sense whatsoever to rescue Booth after Lee's surrender. With the end of the war at hand and plenty of trouble to handle himself, Mosby did the only reasonable thing by letting Booth fend for himself.
With regard to JFK's assasination, I used to be extremely skeptical before spending time some of the Cuban sections of Tampa. Now I'm more inclined to listen.