Unless those kids have a gun in the hand that isn't out, you could say "hasta la vista" and truck on by
Here's the "why"---those kids have moms, and maybe even a dad or two, who do the family grocery shopping. If Stop&Shop was to say no, the organization would tell all those parents that mean old Stop&Shop didn't allow fundraising, and those parents would switch over to Shaws.
My kids play all kind of sports. It costs a lot of money, and the organizations can only ask the parents to pony up so much. They try to keep it affordable and often times let kids play even if their parents can't afford the registration fee. Less than 40% of the cost of running a youth sports league comes from registration fees. The rest comes from sponsors and fundraisers. The same businesses who sponsor these teams are also pretty good about letting the teams make up the difference by setting up tables outside and asking patrons for a buck or two.
It's a fact of life for parents of kids in the organizations---get over it.