Maybe they did the right thing, maybe they didn't. But the crew did walk away under their own power, and had they continued the takeoff, they might have made it and they might not have.
Just as I think V1 calculations, not accounting for acceleration rate, are based on pristine aircraft and engines, flown by test pilots, I also think advertised engine out climb performance is less than we expect. I once lost an engine on a heavyweight 707 at near to, but less than, max takeoff gross weight at 600 feet after takeoff. I could not hold V2 in level flight, and the aircraft didn't hold altitude until 10,000 pounds had gone out the chute. Since then I've been suspicious of the charts. Maybe this captain, who I presume has flown some time to attain the left seat of a 747, had similar thoughts.
We do need to have a decision speed, but we need to temper all the factors in. If I was the captain, now standing at the end of the long mahogany table in his full uniform, with no ashtrays, explaining himself, I would be smug in the knowledge that I'm here today to tell you the story and what I was thinking. He may be fired, or he may get a medal, but he is alive, and all this will pass.
Hats off to him!