Try probing what people think having free will actually means, and you'll quickly see that people tend to react very strongly if you suggest that they don't have some vague undefined ability to take actions that are not defined merely by the state of their brains and inputs.
To me what you describe does not at all match what I've observed people try to defend as free will whenever you peer beneath the vague veneer of external coercion.
> Your definition of it being entirely nonsensical is clearly even worse than this definition for being accepted the way most people use it, since your view implies that there is nothing people mean when then say 'free will', when there clearly is something that is meant.
That is not at all what I meant by calling it nonsensical. I am very sure that people do mean "something" and my experience is that this "something" includes a very strongly held belief that peoples actions can't be predicted based purely on the state of their brains and inputs. Try to suggest to people that maybe they're effectively just machines, and you'll find a lot of people balking at it, because it e.g. would imply no soul or anything to set us apart.
What I meant by calling it nonsensical is that when you start probing into why people hold beliefs like that, you'll find it evaporate as you probe. You'll find people can't put up arguments for, but more critically few can even describe a version of free will that fits their beliefs.
You've given a definition, and that's great, but it's a definition that defines away the problem under discussion - nobody who argues against free will would disagree with you that there exists a feeling of being a choice making agent. We disagree with those who claim that we are choice making agents other than in the same way that an automaton can be.
So you are right in the sense that free will by the definition you have given exists. But that's not the kind of free will most people here who are denying free will are debating.
If anything, the definition you have given tends to be an important answer to those who believe in "hard free will" to disambiguate them for why you should keep making choices if you don't have free will: Because whether or not it is an illusion, we do have that feeling, and whether or not we have control over the choices made, if we don't make any choices we still suffer the consequences. So the only logical choice, illusory or not, is to still make choices as if you have free will whether or not you think we have "hard free will".
That said, once one decides that "hard free will" doesn't exist, it tends to have a significant effect on personal beliefs. E.g. punishment (as opposed to rehabilitation, or incarceration for protection) becomes cruel if you accept that "hard free will" is an illusion - a person may believe they have free will, but if it's an illusion we're punishing people for things they didn't have an actual choice in. (Note that this does not really affect the issue of coercion - a person threatened with a gun to take your example might still be due different treatement than one who did something bad without being threatened, because the latter is still more likely to be a risk to others; but there's a difference between risk mitigation/protection/rehabilitation and vengeance - if it was a truly free choice based on "hard free will" vengeance might well be morally justified, while without "hard free will" vengeance is morally horrendous)