Cool chapter I enjoyed it!
I know people aren't really satisfied with Opera lying and everyone but Mont'dor just taking his word for it but you have to consider the environment they live in. Opera did see his brother get his life sucked out of him just earlier that day, it was under different circumstances but it's still got to be scary. Then you have Smoothy, one of the 3 Sweet Commanders, who told everyone to keep the info about Brook in the treasure room a secret and that was only a few chapters ago. The kids don't want to upset mom because they know they might be getting a whoopin'. I think many of us can relate to that. That's just the environment they live in. As for the random mooks who let Luffy, Nami and Jinbe escape, it doesn't seem like many want to come forward and let anyone know that they were partially at fault either. They know what could happen so why wouldn't they listen to Big Bro Opera or Big Sis Smoothy? Keep that ship quiet and hopefully we can take care of the problem in secret is probably what they are thinking.
I think the problem isn't only that. You also had the soldier sleeping in Sanji's bed without any explanation, nobody asking where is Bruleé, nobody except Mont D'or doubting the Luffy and Nami whereabouts.
It just seemed to me that Oda wanted to rush the reunion and i making up excuses to a surprise attack. To me just the FI's bomb and Sanji knowing about the plan would be enough.