Is it valid to cite the story of Muhammad ibn Maslamah’s killing of Ka'b ibn al-Ashraf as evidence for assassination operations?

Question:
May Allah reward you, Honorable Shaykh. A questioner says: Some contemporary Khawarij cite the story of Muhammad ibn Maslamah’s killing of Ka'b ibn al-Ashraf as evidence for assassination operations. What is the response to them?

Answer:
My brother, who sent Muhammad ibn Maslamah? Was it not the Messenger (peace and blessings be upon him)? He is the one in authority who sent him. The one in authority, who is the Messenger (peace and blessings be upon him), sent him. So if the one in authority sends someone to kill a corrupter, there is no harm in that. This is a matter for the one in authority. Yes.