Volvo is an auto manufacturer renowned worldwide for their commitment to safety. Volvo uses nitrogen to inflate the spare tire on all of their passenger vehicles. And they have been doing it for years. Filling the spare tire with nitrogen minimizes pressure loss and assures it is closer to set pressure than its air filled counterpart. Drivers rarely maintain the tire pressure in their spare tire, so filling it with nitrogen helps to guarantee usability when required.
If it is safer to fill the spare tire with nitrogen, why not fill the four regular tires as well? Nissan is already doing it with their GTR, and it is only a matter of time before all new vehicles have it.