Maybe it doesn't apply to all dogs, but there are probably some that get freaked out over a baby swing. My Ginger will bark and lunge and then run from the broom, so you never know what will set off a dog unless you really know your dog. Ginger would never attack the person holding the broom, she mostly reacts because she's being silly or just has some issue with the "monster" broom. There are several factors behind dog attacks and for some dogs a baby swing could be one.