You have every right to be concerned and it’s very disappointing that the police just brushed it off. As a parent I know exactly how you feel. We just want to protect our little ones! Question though...why didn’t you go up and talk to the guy on the swing? I’m an introvert but have learned from husband to tackle things head on and sometimes you’d be surprised how things go when you deal with them yourself instead of involving, in this case, the police.