There was no 'point', really. To the extent there was a point, it was Moore exploiting a tragedy to make himself feel important by bullying and humiliating others, using victims of a shooting, with whom any breathing person would sympathize, as a wedge to make Kmart choose between playing the horrid monster who cares more about sales than shot-up kids or a responsible company who cares more about shot-up kids than sales.
It would be like Moore waiting for you to get into your SUV, then ambush you using a sickly, pale, 10 year-old girl with severe asthma dragging IV poles behind her. Moore demands that you explain to this girl why your right to pollute the air is more important than her right to breathe and be healthy, all the while cameras are rolling.
While you're scratching your head, befuddled and confused, Moore has carefully crafted an 'easy' out for you. All you have to do is give Moore your 'killer' SUV and promise to replace it with a bicycle, and the little girl will smile, give you a big hug, then say "Thanks for not killing me, Mister". You look like a hero while Moore and the little girl drive-off in your SUV, vowing to have it crushed and recycled into some electric-powered Yugo.
If you don't choose this 'out' and refuse to surrender your SUV to Moore, the little girl will start crying, the stress of which will cause her to start wheezing and gasping, then she'll have to be whisked-off to the Emergency Room by ambulance.
If you understand the point in that, you understand what the Kmart scene in Bowling was about.
Of course, if you have nothing to lose, you might just say 'Get the hell off my property you idiot'. But Kmart can't afford that kind of public relations disaster, it has enough problems without being made to look like the Anti-Christ.