Additional information: he and his partner had arrested a man, who was handcuffed and unarmed in the back of the car. That is whom the policeman thought opened fired at him.
I use Jami daily. The pro is that it is completely decentralised: it doesn't need a server to run, all communications are over DHT. The cons is that not all messages are delivered instantly, and both sender and recipient need to be online at the same time.
I didn't open the article before, and you are right. The author of the article lives in Chicago; I think that Ars has no European writer to really understand what they are talking about.
We are always on the brink of ruining everything nice that we have been slowly building.
You can read here about the plans of the European Commission to enable service operators to mass scan all the users' private messages in search of illegal materials.
The Commission is the same super-government body that signed privacy-oriented things like the General Data Protection Regulation.
He doesn't develop text editors, so he uses what's popular. That's what most people do.