"Would a pistol have been enough to at least scare a grizzly away?"
Actually, I think the question is, "Would two .22 bullets in each of the bear's eyes and several pumped into his midsection at least have slowed him down."
How good is your aim while you're running away from the target?
"If carrying a .22 comforts you, do so. But do not load it, for if you load it you may fire it, and if you fire it you may hit someone, and in doing so annoy him and give him reason to do you harm." - Jeff Cooper (parphrased)