User blog comment:Kaido King of the Beasts/Why Just Have Two?/@comment-24.235.56.170-20150425232636/@comment-24.235.56.170-20150426025145

That seems really unlikely to me. If it were that simple, he'd just do that to everyone. I mean, he had Ace immobilized too, but he definitely didn't take his power.

I'm betting it has something to do with how devil fruits transfer. ie. When a DF user dies, their power moves to the nearest fruit, but BB traps them in darkness so that it can't find a fruit. Then something something Oda logic, and BB gets the power.