Why use a bear banger on a bear that is within spray range? Bangers are not to be used as projectiles or designed for such close range.
Even if you are a rigid follower of three stage bear control*: that guy would be in the slug zone according to that philosophy anyways.
*designed for polar bear control by biologists in field camps and not really applicable to chance encounters with bears imo.
I say:
voice: annoying
yelling: correct but usually laden with more obscenities in my experience
spray application: hippy like in nature
Bear: likely acclimated to people, a CGN member should go shoot it