When my grandfather was still alive but in 90's he took to having a very, realistic shall we say, take on death. he wanted to discuss his death, his plans, the finances etc. he would ask me to go on the internet and research the cheapest coffins, and look into how the family could save on this or that, and he would crack jokes about his impending end, etc.
I was in my late teens. I followed his lead and would indulge his questions, do his research and crack jokes right along side him. We would try to out-do each other with the morbidity and graphicness of our jokes. He didn't mind at all, in fact I think he really appreciated that I would.
My grandmother and my dad though? They were appalled. Offended. Mortified. Angry. You name the negative reaction they were it. And not at him - they didn't like that grandpa talked about his death, but they accepted it - but at me. I got scolded later by my dad 100% of the time (and this was a weekly conversation, so I was getting in quite a bit of trouble).
I think that the letter writer only speaks about her own reaction and not her husband's speaks volumes. I can say I kept up with the death-talk despite getting in trouble for it because it wasn't about my dad, or my grandma. I wasn't happy my grandpa was dying and I understood and sympathized with them over the inevitable future - I didn't want him to die either - but as far as I was concerned, grandpa's life and grandpa's death were topics grandpa got to set the tone for so long as he still could and I didn't care one hoot if everyone else minded.