Every creature is a fungus, which can produce new saproling-sliver-funguses every turn, each of which produces further saproling-sliver-funguses, all benefiting from the slivers' ability.
A fun game is to intentionally allow your team to go into Sudden Death and then stand outside your remaining Control Point shouting "THEY SHALL NOT PASS!!!!.
So the Zerg Rush is just the first part of Nod's one-two punch: wear down and distract the opponent with the Zerg Rush, then send the favored son in the back way to finish the job with mad skills and alien technology.
Notably, the reason that they ultimately lose is that they overstretch their forces, leaving Char open to a decapitation strike by Valerian and Raynor's fleet.