Further, removing the dialogue doesn’t solve the problem of gathering such a large force so quickly. You would need added scenes to do that.
To clarify, I’m not proposing a better justification for assembling the fleet so quickly. I’m proposing eliminating the very idea that the fleet was assembled so quickly to begin with, but rather that it was already assembled by the time TROS begins. Poe’s lines are a hurdle to this change because, as one of the Resistance’s top leaders (and THE co-General by the time of the final battle), he would presumably have some idea of the fleet’s actual size.