Even if there were no legal consequences for provoking someone, just the idea that you COULD have avoided shooting someone is enough for me to want to avoid such circumstances at all costs, no matter what.
I don't know if I could live with myself if I knew that I would not be in the position of having shot a person and knowing that I had flipped him off and sent him over the top. Yeah, I might still be protecting my life and yeah, the other guy probably shouldn't let a middle finger get under his skin either and yeah, the bastard might deserve to get shot eventually but on MY watch, I'll do everything I can to avoid provoking anyone for just the conscience alone.
"Great genius will always encounter fierce opposition from mediocre minds." --Albert Einstein.