The gate and the leg have nothing to do with the other. Those gates open easily for a reason. It's not difficult to understand or figure out.
I'm of the opinion that a lot of fractures and breaks that happen to race horses can be mended, it's just that these horses are nothing more than investments to the kind of people who generally own racehorses, and not worth the money to fix. I hope that's not the case for Barbaro.
However, that's not to say that a lot of things have to go right for a break to be fixed. A lot. And it's true that your average race horse, knowing that today's a race day, knowing that there's a race going on that he/she isn't a part of... well, that horse is in high octaine mode, and as likely to ground its broken bone into shreds than anything else. And there's the problems of operating on a horse.... of keeping even a normal horse calm and sedate, yet alone a highly annoyed race horse...
If the veins are in good condition, depending on how clean the breaks are, depending on how good he is (I suppose) staying still in his sling... and depending on the amount of money they're prepared to pony up, perhaps, maybe, this will just be a looked back on as a bad week in his past.
His racing days are over, but who cares about that anyway?
I've seen such situations (not race horses though) go both ways.