I am going to venture to say that maybe b/c he the housekeeper hadn't found his body yet, that maybe AM could be the one to discover the body. Along the lines of I haven't heard from my Dad in a while could you go check on him, as AM just lived down the block, it wouldn't seem unreasonable. I think it is pretty clear he did not want to be the one to discover the body or make the 911 call.
I'm saying the same even before I read your post.