I don't need for him to start monologuing at all, he could've just started remembering by himself, just like Kaido is also doing
you don't have to tell the other person you're fighting, the flashback is more for the readers anyway, not the characters
it doesn't matter if Zoro knows or not, especially because Zoro still doesn't know, Sanji is the one that got told that
it was pointless for Queen to do it