Sorry to hear of your experience. The one LQS that I frequent most is very open to kids attending events, even retreats, as long as they are not disruptive. That does not sound like the case with the kids you had there with you.
This shop even has a small, and I do mean small, kid area when the kids can sit at a table and color or play peg board games.
How do people think children will learn if they are not encouraging their creativity and allowing them to participate. There will not be LQS in the future if the store owners do not welcome the future generation.