Why couldn't a seventeen year old 'stand his ground' when stalked by an armed stalker?

"For those who resist that idea, I'd just ask people to consider if Trayvon Martin was of age and armed, could he have stood his ground on that sidewalk?

It's too bad Trayvon Martin wasn't armed that evening. I guess if you're under 18 you can't defend yourself against an armed stalker who isn't. I do know one thing that is indisputable; if Martin would have shot George Zimmerman that night, he'd already be serving life without parole.