Unfortunately, since the device contains gunpowder, it is in fact an explosive device, and intentionally setting out such a device outside the building to tempt, attract or lure a culprit/victim.  If a child, it would easily fall under an attractive nuisance to trespass.  

Thus, even printing this story could put RG at direct liability should any reader construct a similar device and comes to/creates harm or substitutes the charge with a real shell or other incendiary devices (fireworks, pipe bombs, etc)  

Considering how gullible people are, you may have all sorts of citizens fabricating such devices in spite of common sense - because they read it in the newspaper, it HAS TO BE OKAY!
which it is not.

IE:  what if a delivery driver/USPS agent came to deliver mail and had to move said device to make more room = you have assault & terrorism charges from a federal employee.  Surprise/shock = slip & fall, and facing full liability for intent, etc.  super duper bad idea...