That should never be happening to you. A team that doesn't take care of the supplicants is a bad team. Everyone has infinite supers while Time's Vengeance is active, they should be making use of them when leaving the central platform to clear out any remaining supplicants. If that's a problem, then one person should be designated as a supplicant-killer for that section. Get them to empty their sniper rifle into Atheon (which , if they're using the icebreaker, won't take long) and then concentrate on taking out the supplicants instead.