His Up+B isn't that bad, imo. It's his DJ that sux and makes his recovery bad ;/
His up B travels in a relatively fixed path with very little flexibility in movement, unable to travel straight up (dangerous on some ledges, lylat cruise) or gain much momentum mid-flight. His landing lag (of the none carry over kind) is relatively unjust. In addition, his "grab" has a relatively close and small registration area, along with a number of frames between when the grab ends and the uppercut begins. It's no saving grace that the upper cut can hit a foe, but not give Ganon back his up B.
His double jump (air jump would be more proper) gimps a lot of his game - from autocancels to recoveries. With a real DJ, Ganon could Down+B spike with greater leniency, he could chase much higher into the sky with Uair, he could possibly even mindgame his reverse-air-Warlock Punch near Falcon effectiveness. He'd instantly climb the tier list, without even touching his lack of approach/pressure game and wtfisthiscrap Utilt.
Nothing new here...
Just a little clip of how you can control your Warlock punches:
I can't think of a reason I would prefer NeutralB in that situation over any aerial.