Without knowing the whole story, I can't pass judgement on the guy. Heck, he happened to be in the right spot at the right time to witness something that most of us will never see. One buck was already dead, so you can bet that the other buck was near death too. So, cutting them free would not, without a doubt, save the other deer. In it's weekend state, it could've been coyote bait pretty easily, or just simply died of exhaustion later.
So, putting the 2nd buck down may have been the better thing to do at the time. Was it a "Great" hunt, maybe it was, without knowing the whole story, I don't know. Now he is selling the racks still attached, what's the big deal, guys sell all kinds of mounts all the time. If he can get $6000. for it, good for him.
This reminds of when a guy gets a deer that is near world record status and guys get jealous when they hear how much money he makes because he got lucky!!