You could tell the horse didn't want to run before the race. And the gate thing. Why did they insist on bringing him back to the gate? I would've pulled him right there.
No, the horse WANTED to run. He was very anxious. That is how he is. He heard a noise when he was in the gate, and that is why he broke. This happens with maidens, they get all excited and they break before the bell. It was wierd, but had nothing to do with the injury. That was a freak thing.
Because it's a horse race. Horses act up, refuse to load, shy, spook or raise hell in the gate, and then run races, all the time. They occasionally false start. The concern early on was that he might have hurt his knees on the gate, not a back leg. No telling if the injury he suffered was even related, or was something else. 20/20 hindsight.
Where did that come from? If anything, he was TOO revved up. That's why he broke from the gate.
Lots of horses break the gate. The risk is not injury, but that they get SO excited that they "leave their race at the post" . . . no reason to pull a horse just because he breaks. Man O' War was a notorious breaker (in those days they just had a cable barrier across the track), he might not have run half his races if they pulled him every time he had a false start.
And I don't think it's greed (why knowingly run a horse who's compromised, knowing he could sustain a life-ending injury?) Unfortunately, racing is a very severe test of soundness and stamina, and accidents happen.
I sure do hope this boy makes it through the surgery and the rehabilitation. Even if they have to fit him with a temporary basket prosthesis and swim him until he's fit to walk, it would be worth it in the long run.