Thought I made this post yesterday but must've forgotten to hit post. Anyhow, I completed the requirements for this triumph yesterday, not dying in a master empire hunt. I got the pinnacle rewards upon completion, see my attached game activity page. I'm curious if this is somehow bugged. I'm sure it's not because others in my fireteam died, because when I got the flawless master lost sector triumph, I was the only one who didn't die in my fireteam as well.