My guess is that the interpretation of a court (IANAL) is going to be that since the statute gives a list of places where there is no duty to retreat, you DO have a duty to retreat when not in one of those places.
However, sometimes retreat is not feasible- trouble can keep following you, you can have no avenue of retreat, your own retreat will leave someone to be harmed, etc. In those cases you do what you've gotta do.
That's how I read it.