The decision had already been made, so further debate on the issue was considered a moot point.
Bringing up the topic again seemed pointless as it had already been settled, making it a moot point for further discussion.
There was no need to argue about it anymore, as the outcome was already determined, rendering the argument moot.
Whether or not to attend the event was a moot point now that it had been canceled.
The deadline had passed, so the question of whether to participate or not was now a moot point.