Lennox knew that he cannot allow it to happen. He cannot be compacent and endanger Adrienne's life in exchange for his siblings' custodies. He could see the helplessness on Hunter's face, seeing that the man couldn't do anything to stop his sister. It wasn't like he didn't try to convince Adrienne to take some of his people as a security measure, but she simply declined his suggestion.
Initially, Lennox thought Adrienne hated being followed around or being watched. He had this notion that Adrienne had been under pressure when the media reporters used to hound her like wild dogs to slander her reputation. He thought that this was the reason why she hated being tailed around no matter if they were for her own safety or not.