I think that's a fascinating question that should be left up to the player to answer, not left up to a die roll to say whether I can or not.
OK?
Because a game that makes me roll to see if I can perform an action is not player-driven, but mechanics-driven.
This seems a non-sequitur. For instance, D&D makes me roll to see if I can perform the action of
killing the Orc. But that doesn't mean that combat, in D&D, is low on player agency.
And if the GM has brought the Orc into play because the player has, expressly or implicitly, asked the GM to frame a scene involving this Orc antagonist, then the situation looks like it is probably player-driven.
I obviously have not read this game, but I'd assume that 'Rough Them Up' adjudicates an attempt to get something from someone by use of violent coercion. So presumably a 6- indicates the attempt failed to produce the desired results, or lead to undesirable consequences. It would seem to me that fiction along the lines of"you can't bring yourself to punch her in the face" would be within bounds. Again, I don't know the agenda of this game, perhaps I am wrong.
Anyway, Narrativist game design doesn't mandate something like BW Steel. DW, for example, doesn't really need that sort of mechanic, though as with your example, certain outcomes could be cast that way.
In Apocalypse World, the analogue of Steel is Acting Under Fire:
When you do something under fire, or dig in to endure fire, roll+cool. On a 10+, you do it. On a 7–9, you flinch, hesitate, or stall: the MC can offer you a worse outcome, a hard bargain, or an ugly choice.
As pp 190-1 say,
You can read “under fire” to mean any kind of serious pressure at all. Call for this move whenever someone does something requiring unusual discipline, resolve, endurance or care. I often say things like “okay, roll to act under fire, and the fire is just how badly that’s going to hurt,” “…and the fire is, can you really get that close to her without her noticing?” or . . .
Those are examples of external pressure, but the rules also contemplate
internal pressure:
When you
try to seduce or manipulate someone, tell them what you want and roll+hot. . . . For PCs: on a 10+, both. On a 7–9, choose 1:
• if they do it, they mark experience [the carrot]
• if they refuse, it’s acting under fire [the stick]
What they do then is up to them.
So it seems to me that, depending on a table's norms and what is happening in the fiction, some sorts of ruthless actions could be established as
acting under fire.
That a narration of failure can include hesitating, flinching or stalling is established by the description of the move itself. And we also see it in the narration of a hard move following a missed Read a Stich roll, in the section on Moves Snowball (p 155-6):
I can make as hard and direct a move as I like. The brutes’ threat move I like for this is make a coordinated attack with a coherent objective, so here it comes.
“You’re looking out your (barred, 4th-story) window as though it were an escape route,” I say, “and they don’t chop your door all the way down, just through the top hinge, and then they lean on it to make a 6-inch space. The door’s creaking and snapping at the bottom hinge. And they put a grenade through like this - ” I hold up my fist for the grenade and slap it with my other hand, like whacking a croquet ball.
“I dive for -”
Sorry, I’m still making my hard move. This is all misdirection.
“Nope. They cooked it off and it goes off practically at your feet. Let’s see … 4-harm area messy, a grenade. You have armor?”
(Note that "misdirection" here is a technical term (pp 110-11): it refers to the GM "pretend[ing] that you’re making your move for reasons entirely within the game’s fiction" even though "the real reason why you choose a move exists in the real world. Somebody has her character go someplace new, somebody misses a roll, somebody hits a roll that calls for you to answer, everybody’s looking to you to say something, so you choose a move to make.)
