His other attacks are useless as well.
Luffy's willpower was simply over the top during the fight. That's why Zoro tanked tons of shit in TB, Luffy enduring tons of shit in ID and MF, Luffy enduring that shit in Enies Lobby - doesn't mean Kuma's, Magellan's or Lucci's AP was trash because of that. This is a prime example of Luffy's entire willpower trying to surpass the 1billion berry dude.