I don't think a roommate would know someone just died or that someone coming in had blood on shoes etc. I think it is fine to set boundaries, but I disagree that the room-mate should consider their stuff petty minutiae. I don't think either one is more important than the other.
I was doing death penalty work while my person was getting tenure. When I would come through the door, it was mostly hearing about her day at school. For me, while I certainly thought the stuff she was describing was sometimes silly spats between faculty members, it was stressful in terms of a livelihood - no tenure- no job. Sure my guy was going to be dead, but the truth is I did not get him there and there were limitations on what I could to save his life. So in some ways, her situation was more stressful than mine. And to be fair, I would not have talked about my stuff much anyway - so she might as well talk about hers. I think the trick is not listening all that closely. We did have an agreement that I would have 30 minutes after I got home to not have talking.