I doubt if anything will come of this.
I don't know what state you're in (in a congested area, such as CA, they don't have time to follow up with 'sightings'), but you could wind up with sex offender registration for an act in public, if you do it again and get caught by a cop (or, at minimum, embarrassment and a fine- remember Hugh Grant?).
If you get caught 'in flagrante', they will probably nail both you & your accommodater for immoral acts in public view (this isn't the best thing for little Johnny to see when he passes your car).
My guess is this security guy didn't want to pursue the issue (he knows he'd be called as a witness & he was youg once [you are young, aren't you ?]), or the cops are too busy to follow-up.