You don't even have to go so far.Several European countries consider physical letters to be confidential.https://en.wikipedia.org/wiki/Secrecy_of_correspondence
Strangely enough that confidentiality suddenly no longer applies to other, "newer" forms of communication.Probably because it's less easy for security services to ignore.
While I agree that "died" would have been a bit more neutral, killed is not wrong.
A common expression is "It's not the fall that kills you, it's the sudden stop at the bottom."In this case neither the fall nor the sudden stop are people but they can still "kill" you.
The "living thing" in the quote above refers to that which is killed by the way. It's the object, not the subject of the sentence.