It's a bit more about revoking the method. I think that if I were to write self-revoking subroutines that I'd be operating in an environment where an object returns a method (read capability) keeping a copy of the object and itself as a closure. This is what an object revoking access from another object might look like. Or maybe not. Anyhow this is just a tool - whether it's a particularly good one or not... I don't know yet.