Mrrz, a hard but necessary line to teeter-totter on (for you) is that you want to respect his freedom/choices but you also have to remember that detox is just the start of getting the stuff out of the system and the brain not yet physically able to be in charge-- so keep in mind that most of what he says at this time will be the addiction talking, no matter how much it may mimic the person you know and value. Your best bet in that circumstance is to be sure his bodily needs are met and encourage him not to talk much-- by seeing to him briefly and then getting on with your own stuff and then checking back often. Stay detached and in your own reality-- busily nearby but not "in it" with him. The advice to contact AA people for onsite help is also good. They have seen it all and know how to do what is best as it comes up.

Also-- who has told you his status? Do you have medical talking directly with you.... or is this "I just need a bed today because..." "news" some maybe-more-complex reality filtered thru the nephew's perceptions?

~Susan