[tomafro]

He should also define respond_to? on the DoNotDisturb class. Relying on method_missing to pass calls to respond_to? to the proxied class will not work, as it is defined in Object. Responding to a method when respond_to? returns false breaks the class contract.

[nusco]

From the OP: I agree with you guys (or gals) on both calling super and redefining respond_to?(). Those are two of the "caveats" I mentioned at the end of the original post. I considered mentioning them explicitly, but the post is long enough already.