If joining the Reserves tips her employer over the edge, she might be able to claim that she was fired for joining. It would be partially true.
Something I would suggest is he look for alternate routes to the new location. Even if they are slightly longer the savings in fuel, time and wear and tear on his nerves (and yours) could well be worth a few extra miles.
Sometimes the “surface streets”, as we call the non-highway streets here in ok, are far less congested and easier to use than the main highways. Often my guys come home a different route, veering around wrecks and go through a small town about 5 miles off the beaten path and come the country roads home. As a result they will get home a good 30 minutes to an hour faster than if they had stayed in the traffic jam. Just a thought.