yeah I think Jack was just a little drunk, a lot depressed, and kinda spaced out on the drugs when he told the other doctor to go up stairs and see if his dad was drunker than him (hmm drunker, probably not a word
oh well)
The other doc and a nurse gave him a funny look like " what are you talking about Jack, your dad is dead??"
I think Christian Shepard is dead, but just my opinion.