Whereabouts of the spaceship is –according to Noland- 30 yards (roughly 27 meters) away from the predators' camp. Therefore, the time you need to reach the spaceship from the camp and return to the camp again - without staying there more than seconds- is within a few minutes. And when you have a predator to do this, considering its superior speed than that of humans, the amount of time needed for such a to and fro, shrinks a lot, say, well less than a couple of minutes. In this very short period of time, how in the world could Royce take out Isabelle and Edwin from the pitfall, stab Edwin in throat with his own poisoned scalpel, drag half-dead Edwin to the center of the camp, attach six grenades to his chest and fasten their pins to the ground with some string to set a booby trap, pour gunpowder around the camp, cover himself with mud to conceal his heat signatures (where did he find mud or find water to make some?!), and get to cover and hide??!! Mission impossible dude!