The “transcript” of the supposed conversation between Ruby and Oswald is a joke. Imagine the idiocy of planning to get rid of Bobby Kennedy by shooting President Kennedy.
Shuuurrre....
One of the many mob theories has this angle as well.
Santos Trafficante said to Jimmy Hoffa that if you cut off the head of the dog, (JFK), the wagging tail, (Bobby), dies, too.
Later, on November 22, when Hoffa first got word that JFK had been shot he supposedly said, “Bobby Kennedy’s just another lawyer now.”