Well, it's official now – Luffy is going to eat the bento box. The meat virtually assures it. IT seems particularly in this chapter, Sanji is subconsciously thinking "This is Luffy's food, hands off!" when attacking Bobbin
Also, it does seem like Sanji is aware of exactly how the Vinsmoke execution is going down -- knowing that the other vinsmokes won't be killed unless he is killed first. In addition, Reiju's willingness to be killed alongside them seems to have rubbed off on Sanji in some way though Sanji instinctively knows that this isn't right and that the Straw Hats still need him no matter how he justifies his sacrifice.
@Maju:
how big can that castle be that there are "rumors" instead of reports? seems a little too convenient that the sons don't know about jinbe,nami and luffy escaping, despite them roaming the castle just a couple of minutes before.
I'm willing to give the benefit of the doubt here. Firstly, the use of the word "rumors" could easily be Mangastream being loose with the translation. Secondly, the word of a sweet commander would overrule all other reports in addition to the collective knowledge in the room that Opera would be roasted alive on a spit by Big Mom for telling such a lie, so they are trusting his word assuming he wouldn't dare lie about such a thing.