It was suggested to me, also in an interview, to suggest to the person concerned that they remove themselves from any possible situation by developing a sudden illness. Failing that if they don't feel there is a problem then remove yourself with a sudden illness! Makes sure that you are not a party to their disregard for the law and also provides some additional time while another crew member is located, who will then have to make their own decision. Removing yourself from the situation does not absolve you from making sure that that person does not fly. I think most pilots would remove themselves if someone had suspected that they were still under the influence and mentioned it to them directly.