Why didn't John Garrideb like the idea of including Holmes in the hunt for the third Garrideb?

Holmes was a detective, and a renowned one. John Garrideb was afraid that Sherlock Holmes and his partner Watson will suspect his motives and will jeopardise his plan. Involving a detective in a plan that had a fake story, other that the fact that Garrideb, alias Killer Evans, who had a criminal background was not safe.