…I meant.
They sensed somehow that HE is not HE and that HE is actually THEY.
That_just_cant_refer_his_crew.
It's like if some random characters who met Luffy alone would say that "Luffy is actually they, lol."
Luffy, Zoro or anyone else haven't had that kind of conclusion ever after or before that scene in Jaya. So it meant clearly something. On the top of this, there is much information about BB having something odd within him, having two DF-powers and such. When Marco said to other WB commanders that "As you all know, teach is a bit different" It means that they have somehow found out about BB's atypical bodybuild. Maybe they found it out same way, sensing it. (with or without CoO, but i think that it may be the case since WB pirates are able to use haki.)
On a side note, i dont believe in any cerberus-shit-theories, because BB would have most likely used it against Ace when he had to fight for his life. Also, three heads come from same body so it is so absurd to think that he was able to eat more fruits because of that.
And, i just wondered how Luffy and Zoro sensed that thing, so i thought about CoO or pure instinct. So no reason to get in the corner, lol.