The move that Sebastian made was enough to disguise the truth.
He did not want to tell Marcus that someone wanted to take advantage of them and destroy both the Ford Group and the Shaw family simultaneously.
Sebastian let Marcus and the entire Shaw family blindly misunderstand that it was him who had gotten a person to pretend to be Marcus and then have Yvonne killed. Then, Marcus and his parents would hate Sebastian to their bone. That kind of deep-seated hatred could not be faked.
Even when