I note that the Maine (could have had a CCW) resident was chased for 15 miles from Maryland (where he could not carry nor even have accessible his Maine-legal CCW) before being forced, disarmed in principle and fact by act of Maryland law, off the road in Pennsylvania and killed.
Even if Maine and PA had reciprocity, or he had had a FL or Utah CHL, MD's requirement that the weapon (had he had one) be absolutely inaccessible would still have made it impossible for him to have re-armed himself in time to defend himself.
Even given the "ifs" (did he have a permit, would he have had the gun, would he have had time and ability to use it), even if all of those answers were "yes", Maryland law and Maryland law alone would -still- have prevented his opportunity to defend himself.
Maryland owns his death.