There was a case in San Francisco about 20 years ago where a guy in a car saw a crook steal a purse from a lady on the sidewalk. He chased the perp with his car and ended up crushing him against the wall of a building. The perp was very seriously injured (pelvis crushed, IIRC) and he sued. The judge agreed that what the driver did was serious overkill (no pun intended).
There is an old principle that you can only use 'deadly force' to protect life and limb, not property. I often ask gun rights people, if you see someone breaking into your car, parked on the street in front of your house, can you shoot him? About half of them get it wrong. The law says you can't. (Unless he's black, of course, and then it's open season.)
So, setting up a gallon paint can on a rope to knock someone backwards down a flight of stairs--could that be considered 'deadly force'? I think so! Funny but potentially deadly.
You're totally right. If the perps lived they could sue Kevin's family (who, judging from the size of the house, were not 'judgement-proof').