Not sure what you guys mean about the start position, but I think that's much more legit than starting with your hands down, fingers halfway curled up your hem.
As far as shooting before full extension, that's how you get those speeds. You have to cut corners. No one can repeatedly make 90% hits on a down zero at 7 yards at that speed. I'm not saying the .53 or.54 draw is a useful skill, or a legit ability, but it is fast, there is no question about that.