I think Martin's "random deaths" work better for the only reason he is a way better storyteller. The examples written by Ken worked a lot better than the original ones quoted by Seri, for example, to my opinion.
You also need something else for grimdark to work. For every gloomy thing, creepy aspect, you need at least some of the opposite values. If you have none, you can't adjust the contrast (because there is suddenly none), and voila, tasteless whatever you try to achieve, because you have no 'good and emotionnal' reference anymore.
I think here the author tried to do kind of the same thing Gaspar NoƩ tried to do in his movie Irreversible. Some things work, while some other just look gratuitous. But unlike the movie, text based crude scenes are hardly very relevant when they come to that. Either you have to describe a lot more to make the player feel really dizzy, either you have to be more subtle to let him come to his own gloomy conclusions.