I've helped organize two British Schools Exploring Society Expeditions -- Iceland 1985 and Montana 1994. I was pretty sad to hear of this horrible incident.
But polar bears are in trouble and will be getting hungrier and hungrier as summer shore ice retreats from places like Svalbard. Trip flares and rifles won't stop a hungry bear.
I ran expeditions for years in grizzly country without a single serious incident and learned something about bears from a few close calls we had.
My buddies from Montana who used to do wildlife film-crew protection in Alaska thought sawn-off pump-action shotguns a better weapon for grizzly and polar bears. Air horns work well for scaring off bears in the first few minutes, as they approach the camp, and for waking the rest of the group.
And posting sentries around the clock is probably the way to begin to protect the camp.