I'd prefer a more elegant solution. Explain to him that we can't protect him from the consequences that will emerge if chooses to sever ties.

They like to believe they know everything, too blind to see there are two versions of truth - the one everybody knows, and the real one. Or perhaps they're afraid to shatter the illusion, afraid to even attempt to leave the comfort of their cage and the false sense of security it provides

Intentions alone are meaningless, only actions and their results matter! And your recent actions have yielded remarkably poor results.