[B.T.]

Some quotes, I can relate to:

Quote from Rainbow Six:
"When it comes to executing prisoners, for me, I think a lot depends on context. I’ve played in games where the PC’s have been operating well away from any friendly support against some pretty blood thirsty marauders who have done some pretty unpleasant things (the marauders, not the PC’s). The PC’s were only passing through the area and did not have the resources to take and hold prisoners (nowhere to put them, no manpower to guard them, and would have to feed them from their own limited rations)."

Quote from SSC:
"... yes, I like to include moral dilemmas and ethical quandaries for the PCs and I like to let the Players have the agency to make those decisions. However the full weight of consequence hangs over them if they deliberately choose to do a bad/malicious/evil thing. Sometimes circumstances force good people to do things they would rather not do, I don't want to punish Players for that because I as GM put their PCs into that situation in the first place, specifically to cause them that dilemma.
Do you let a traitor live because he was blackmailed into becoming a traitor? What if leaving him alive will cause the injury or death of innocent people?
Do the PCs ignore a job they don't particularly feel comfortable with or do they let some group of lowlifes take the job with the chance that the lowlifes will harm a lot of innocent people?
I tend to think these situations will never have a completely right or completely wrong answer and so they are good tools for the GM to make Players think about the actions of their PCs."

Quote(s) from Legbreaker:
"I'm 100% with SSC here. Consequences are the correct answer, not restrictions on possible actions.
On occasion I'll thrown in a morale dilemma, but only to make the point of consequences. If the players have been acting in such a way as to invite retribution or retaliation, then it WILL happen.
Rape, murder, child abuse, etc is all on the table, however the details will absolutely be glossed over where possible except where absolutely necessary to describe the "wrongness" of the situation and (hopefully) encourage the players to seek another path."

"Our next question is what do you do about "slavers" who turn out to be basically prison guards putting convicted murderers, rapists, etc to work alongside POWs?
Add to that the resource the "slaves" are producing helps upwards of 100,000 people survive....
Their encampment serves as a major trading hub with the much of the regions economy reliant on the main product of the slaves as well as the additional trade.

To me, T2k must have moral dilemmas. This one started as little more than a random encounter (several really) and is turning into a major regional issue."

Well done, everybody!
I think, T2k - or any other roleplaying game - should be an enjoyable social thing for GM and players. If a party likes it rough, that's their thing - it's not mine.
But the world in T2k is gritty. Slavers, rapists, former organized crime figures, warlords and so on live in that world. The moral dilemmas for my players are part of MY way to play that game. All of my players are grown-ups, the youngest being about 30 years of age. I would label all of them "experienced gamers". The games include Call of Cthulhu, Shadowrun and a million-zillion fantasy games.
I can mention all kinds of evil things, but I don't have to go into too much detail.
When PCs act extremely violent, they will have to take the consequences, just as several of you have mentioned earlier.
And to emphazise this: Know your players!!!
I know all of my players for more than 10 years, with one exception. I know, how these guys are thinking.

And one thing, that was not mentioned above: As a GM, you allways have NPCs, you can use to balance the ideas of PCs.
In my group, no one (of the player, this is!) has military experiences. I am the only former soldier (and I was "just" a conscript). The group contains several NPCs, that are part of the group. And some of these had been in charge of a platoon or company in the earlier stages of WWIII. To make this clear: From time to time, a lot of NPCs accompany the player party, but these usually leave the party at a certain point (geographically or in time). The NPCs, that are a vital part of the party are five. One is a former platoon leader of the USMC, one is a combat medic, two are drivers.
These NPCs have a vote, if the group has to make decisions. And at least the former Marine has a lot of exerience.

If one of my players is about to do something really stupid, I have the NPCs to give additional info or to adress problems, the players did not think about.

T2kshould be gritty, but I have a vague idea about my red lines.