Not because this is a correct interpretation under their communication culture, but because they literally can’t track the distinction, without slowing down or using a diagram or something.
I’m unsure but I suspect that in many cases you’re thinking of, this is incorrect. I think people can track implication when it’s something that “makes sense” to them, that they care about. I suspect that at least in a certain subset of these cases, what’s really happening is this:
They believe not-X (in some fashion). You start trying to say “X implies Y”. They get confused and are resistant to your statement. When pressed, it comes to light that they are refusing to think about possible worlds in which X is the case. They’re refusing because they believe not-X (in some fashion), and it’s pointless to think about worlds that are impossible—it won’t affect anything because it’s unreal, and it’s impossible to reason about because it’s contradictory. (They wouldn’t be able to say all of this explicitly.)
I’m unsure but I suspect that in many cases you’re thinking of, this is incorrect. I think people can track implication when it’s something that “makes sense” to them, that they care about. I suspect that at least in a certain subset of these cases, what’s really happening is this:
They believe not-X (in some fashion). You start trying to say “X implies Y”. They get confused and are resistant to your statement. When pressed, it comes to light that they are refusing to think about possible worlds in which X is the case. They’re refusing because they believe not-X (in some fashion), and it’s pointless to think about worlds that are impossible—it won’t affect anything because it’s unreal, and it’s impossible to reason about because it’s contradictory. (They wouldn’t be able to say all of this explicitly.)