Drk.Pch, it has zero knockback if you CC it. So, while he might be able to get the full thing off, he can never kill with it, and, as such, it is not a threat. You can also CC a sweetspot fsmash and live to insane percents. Really, his best move is his neutral b, and normally, only in the air. It's his only move with true range, and alright knockback.
Why would you be in the zone where he could hit you with f-b in the air, anyway? You should float just above it, if at all. This is a battle where you should control the ground, because the air is already yours.