173 didn't understand the words of humans, or any creatures, for that matter. It was techically sentient, but it's only motive was to snap the necks of every living creature, and automatically turn to statue when seen, so Jane's words could'nt have processed. And another thing, it couldn't possibly run away, it was drivin to snap necks. And what could she do? You can't kill a statue, so it stood there behind Jeff, waiting for the time when they weren't looking.