Reb eliezer
“he question in Binyan Tzion 170 was about learning about an illness by autopsy for other similar illnesses that might occur.. ”
You are mistaken the Binyan Tziyon argues on the Nodeh beyehuda and never allows nivul hames for pikuach nefessh (unless had permission ahead of time) . He has 3 teshuvas all in the same area. he is quite clear on this
Yes most argue (though none make the case that the OP made, “of course killing is worse it has a worse punishment”)