A serious G2/G3 Luffy who makes use of FS+adv.CoA, would beat the crap out of P1 and Ulti. But we know Luffy. He likes to goof around and receive more damage than necessary. Yeah, he wanted to use G4 when Ulti grabbed him, because by now he can use G4 pretty casually (even using it on the fodder beast pirates ship when fighting along with Law and Kidd) and he wanted to end things quickly without wasting time.