This is not Donovan's "home", as the article states. It's his house and rental business. And he was snooping on his guests when he was taking the rubbish bins out and happened to notice cables and people typing on laptops inside the house - which I'm sure is an explicit violation of Airbnb policies.
They turned off his security cameras so he went to take a look. At least that's the impression I got.
I'm a little surprised he didn't knock and ask to go in.
How could seeing people in a house from a public area possibly be an explicit violation of policies?
> Hosts are allowed to have exterior security cameras and recording devices, and are required to make sure their location is disclosed in the listing’s description (ex: “I have a camera in my front yard,” “I have a camera over my patio,” “I have a camera over my pool” or “I have a doorbell camera monitoring my front door and the hallway of my apartment building.”)
https://www.airbnb.com/help/article/3061