the only reason piers managed to survive that long while transformed is but one:
he had to make it to the end, didn't he? he had to sacrifice himself and have that scene where we see him giving up living in his own eyes and rips our hearts out.
but by the time he's next to the escape pod, his arm is twitching madly and acting out. he's losing control. he knows this.
so no, even if he had managed to escape, he would have mutated more and more, porbably even killed chris in that pod, not to mentio haos would have won since there was no one to kill it with one final blast from his mutated arm.