All upset about rogue bating? Let's be honest, even if he didn't run into the grenade, he would have just turned went rogue and killed that guy anyways.
The moral of the story is they allow a chance of Griefing in the game by design. Before there was penalty, and it was a choice, now there's no reason not to rogue. It was inevitable though because once people got geared they would go rogue and grief anyways. There's people that will find ways to grief others in games not like this. This game caters to them, encourages it, it's a love letter to them blocking progression is what people get off to most.
Curious to see how it plays out though when ubisoft sees more and more people quit playing, and the griefers only have other griefers to play against because people just do pve, or just quit. The DZs are a ghost land now anyways. And if you see anyone in there, expect to get shot so shoot first.
The thing that's a shame is that the main feature, risk/reward for going rogue, has little mystique and value to it anymore.