BUt he chose to stay on that path because he did not want "everyone here to die". Desmund used free will to save people.
Actually - in watching this epi again...the lady in the ring shop says that he has to turn the failsafe key or "the rest of US would die." We've long talked about the whole "Us vs. Them"...
What if turning the key was to save the Others and not our survivors...?
I didn't record. Did she actually say "turning the key" or "pushing the button" would save them.