Sanji's weakness is for when He is attacking, I pointed out this weakness last week, He doesn't attack with mindset of also avoiding his opponent's attack,
Zoro vs Ryuma or Mr. 1 for example, He hits them while not getting hit, but Sanji against Mr. 2 for example? Or Jabra? He attacked without caring how much damage he takes,
But don't apply this weakness to when Sanji is being attacked and isn't trying to attack himself at same time, Ivankov didn't say Sanji prefers to stand still and commit suicide letting his opponent hit him, he only talked about how he beats his opponents without caring how much they hit back,