Think this is a very grey area as thankfully its not very often it occurs.I was also trained that if a pax dies you cover them up with a blanket put an oxygen mask on them and make it look like they are sleeping.Also as said above you also have to think about the family.But lets say you are flying on 180 min etops and the customer was traveling on their own.I know that myself that i would not want to sit next to a deadbody for another 3 hrs.Im sure that 99% of pax would feel the same.So you then have the problem as mentioned above of taking them to a location out of site but that would involve a scene in the cabin as said before above.At the end of the day i dont think there is a right or wrong solution.It one of those situations where you "play it by there"