A dozen passersby couldn't share their oxygen to get him off the mountain? No, they all said to themselves, "I didn't pay a hundred grand to make it 99% of the way and abort to rescue some guy 300 m from the top." I suppose it's like the unwritten rules of baseball. Climb the hill, accept that risk.
Stopping to share your O2 means you don't have enough to get back down the mountain. They only bring enough O2 to make their trip both ways.
Think of it in terms of two people out in the ocean 10 miles from shore, one with 50 lb of weights locked to their legs. Do you stop and both die?
Actually we have no idea how many offered him oxygen...I had read reports of people who did. Sorry, but you take your own life in your own hands when you participate in extreme sports.
"Sharpei diem" would be instead 'Every wrinkled dog has his day.'