Yes, I'm upset when I see businesses being clearly anti-gun. But let's take a broader look. Alcohol and tobacco are legal products too. In fact, in many progressive camps (New York), as much as they vilify cigarettes, they would rather have you smoke than own a gun.
I'm o.k. with boycotting Staples, as long as each group gets equal representation for Staples taking a stance against many legal activities. (Did they deny grocery stores and gas stations that sell alcohol and tobacco?)