Albuquerque was a person driving around town with a fake police vehicle and uniform impersonating a Cop. Knowing a lost kid will probably trust park staff and that kilts are uncommon on the street, I can empathize with Busch Gardens on one side. But the kids need to know to look for the identification badges that all the staff members must wear.
I will bet that Disney has a similar policy about guests dressing like Goofy or Snow White.