Because characters can lie, duh !
Did Sanji used Hell Memories on Luffy ? No.
Did he used Specter on him ? No.
All he did was Concassé and Diable Jambe, two techniques which haven't been that impressive in the NW. And Luffy, beaten down and refusing to fight, tanked those for a while. It'd be like Luffy only using Gear 2 and being "I fought with all I've got".
I mean, come on... Try at least.