With all the ethical arguments put aside for a minute...
That thing would taste horrible. Not only because it is a dark boot, but because a 6 year old buck like that is equivalent to a person who is 120 year old body builder. The meat of those fish will never be as good as an equally dark fish in the 5-15lb range.
I've eaten a 70lb king before. Dime bright. Fresh from the water, tasted like crap. I would trade all the meat for a 3lb jack king in a heartbeat.
Same with Butts give me a nice 25 - 60 for eating. barn door size fish are just that eating a barn door. LOL