David's approach to who he thought was the nasty truck driver

Yeah, it's probably not the best thing in the world to be openly angry at some macho trucker guy who is already messing with you in what amounts to a killing machine.

I guess by the time David thought he had his guy, he was too rattled to think rationally and try a more manufactured approach.

I interpreted that scene to mean that David was finally forcing himself to be assertive and overcome his timidness, albeit his hesitant personality was also preventing him from confronting the driver (it also didn't help that he had no idea which one he was). From the conversation he had with his wife on the phone it seems as though 'Steve Henderson' had behaved very inappropriately in front of his wife and David did nothing to stop it so it seems as though he is a bit of coward. The rest of the movie is building up to David overcoming his personal inhibitions, represented by a lunatic truck driver.

So in essence, it may be odd, but it seems to be a genuine depiction of a man who is out of his depth standing up for himself and being assertive, but out of desperation he is going beyond his normal self.

"And what about the sh*t weasels, the ones that blast out the basement door" - Col. Curtis

That scene makes me cringe so much.

David's a wimp at the start, reflected by the conversation with his wife and not punching out the guy who hit on her, now the big phallic truck is after him and he has to unleash his inner beast. He's a bit dismissive to some of the people he meets on the way as well, you can see how Spielberg continued the beta male theme with Brody in Jaws.

I love this film, but the moment he realises he won't make his appointment he shoulda just turned around anyway.