The thing about the “invented scenario” is that it’s exactly the same as the OP: a plausible explanation for how one observed result (ie someone getting angry and gesticulating) came about.
The OP makes it fairly clear, even if implicitly, that he came across a scenario and then retrofitted the explanation to it. Which is exacly what Psling has done. It just happens to be a different one.
Given that Psling’s “scenario could have been exactly right…But why jump straight in with it?” why wouldn’t you ask the exact same of the OP?
All we know, assuming the facts in the OP to be true, is that one person seems to be angry with a driver and that there are at least two plausible explanations for it. It seems odd to use “knee jerk reaction” to describe the second one that was offered.
Anyway. This…
Sometimes we (they) don’t do ourselves any favours.
…is clearly silly. You (not we) aren’t doing me (us) any favours by perpetuating this tosh.
😉