Talking as a passenger, I dont think and hour would present much of a problem, but to sit beside a dead body for 10 hours would freak my wife out for sure, and she would not be comfortable climbing over them each time she wanted to go to the toilet. Not an expert, but how long does it take rigor mortis to set in. I appreciate unless a doctor is present to certify death then there might be a view to presume the person could be still alive but be in a coma or unconscious, but if rigor motis has set in, that shoud be a serious clue. I can appreciate the points about diverting, but surely in a large wide bodied aircraft on the long haul flights, there must be a corner somewhere they could stash a body?