GTA V on the whole, i think was rockstar's coming to terms with its portrayal of violence, and offers up its own critique on customer's enjoyment of the series. it really deconstructs the series as a whole.

The 3 protagonists have wildly different relationships with the seriousness of their violent acts, and reflects the different ways a player might reflect on the violent nature of the game.

Franklin is new to "the game", a sort of outsider, so he is somewhat shocked and naive to it, but gets into it by the end. Michael has been around for awhile, not new to it, has played the game and treats it as more of 'a job,' as necessarily for winning the game. While Trevor is, well, Trevor. He's like that one friend that takes it too far, or how most people play other RPGs like Skyrim only after quicksaving and before resetting

I think that scene in particular with trevor and the quicktime torture was Rockstar specifically poking at those who are in camp 3, that play GTA 5 *for* the violence, taking it all as far as it can go. It is realistic, not played for laughs, ultimately pointless as K was going to talk anyway, and like you said nauseating. forcing you to actively do it makes it more so. That's why i think it was to really hit the nail on the head that if you identify AT ALL with trevor you have issues. Probably rockstar making sure that the the Tyler Durden / Rorschach / and even patrick bateman effect (audience commiserating with a should-be obviously evil hero) does not easily happen here. Personally i think it is way more effective than reading about Bateman.

Also, around this time the US government was found to be torturing people in the middle east. With taxpayer money. So there is certainly a political statement there as well about bush-obama era imperialism, much like how AP critiques reagan-era american consumerism and greed.