Comma usage to express the point in time

The comma seemed to me to be an attempt by the writer to disconnect "before the meeting" from "what's needing completed". That would mean that the things that need to be completed may not be prerequisites to the meeting itself, but just stuff that has to get done. If the writer meant to speak of prerequisites to the meeting, there is no earthly reason to put a comma there.

I admit that a point against my opinion is the fact that the writer could have said "Before the meeting, I'm noting down what's needed completing."

To my ear, this sentence is contorted and, as we have seen, ambiguous. Why not either "I'm noting down what has to be done in preparation for the meeting" or "Before the meeting, I'm noting down what has to be done."