Having a GPS location doesn't mean you have a suspect. Unless the person called from their own property (zero chance) or didn't move locations at all after making the call (very unlikely), it would require a substantial investigation that most departments aren't able or willing to do, because the odds of catching someone would be extremely low.

No, but it means that an apparent eyewitness to a hostage situation who isn't at the location they claim to be shouldn't be believed.