While this is true. The problem is sanji is also piss poor at sensing the INTENT of the individuals talking else he would have known that it was a trap. Added with the fact that there was no one relatively strong in comparison to the three there (jinbe luffy and sanji) it makes sense why their attentions wouldn't be focused on that particular location even when sanji told them to do so
You are giving qualifications and assertions of that situation that Jimbe and Luffy could not give, because they remain oblivious to it all.
Sanji's failure to futrher properly discern intent afterwads is explainable by his emotional state, as we've seen with Katakuri how said emotional state affects one's CoO. Sanji got caught up in the apparent danger that the woman was in, and thus neglected further investigation to rush in as fast as possible.