A little "toot" and rolling down the window with "hey, dude, I'm going to go around you" would have done. No need to get out of the SUV and get all ragey. Christ, people have become nothing but a bunch of selfish a$$holes, and it seems to be rising in terms of socio-economic status.
I have two distinct groups of students, one is very low in terms of socio-economic status. Sure, they're difficult to motivate for many reasons, but they're incredibly respectful. My "high-end" students feel entitled to whatever they want (which their parents normally provide) and can't understand why the rest of the world hasn't seemed to clue into the "we get everything we want, when we want" rules they live by.
It used to be that if I were going to be tailgated, cut off, or whatever, it was typically someone driving a bit a wreck. Now it's $60K pick-ups and SUV's.