Personally, I think the crew did the best they could in a difficult situation.

I would bet that there were at least some children on board in Economy.
Moving the body to the relatively low population business class is the best solution in my opinion. Save for the distastefull and disrespectfull option of jamming the body in a cupboard or toilet.

As a person in charge, given the rather limited choice, I would rather put the body beside other adults than leave it where children are present.

Call me crazy