He was killed by a car being driven by somebody who was evidently not paying enough attention. Beyond that we know nothing.
I’m glad you conclude there is no causal link between your displaying your disinterest and what happened to the man.
We should worry more and act to predict and stop those men, the ones with fragile dainty egos, who can’t take a refusal and convert their feeling bad into violent action against the world.
Like you said, “There should never be ramifications for communicating that you are not interested any more than there should be standards for how you are expected to communicate that.”