According to the NPS account and investigation of this incident, the spray and bullets reached the bear at the same time. If that is the case, this incident is irrelevant to any spray vs. bullets discussion -the bullets weren't backup for the spray in this case.

While in theory, I prefer bear spray, when Mr. Griz is ten feet away, as he was in this case, I would probably be very happy with a slug loaded shotgun in my nervous little hands.