Okay Col - here goes.
Is it wrong to deliberately wind someone up looking for a reaction? I'd say "yes" pretty much all of the time... but here's the tricky bit, you need some form of context around it.
I don't see my initial applause and shaking of head as "winding up" - it was a display of my displeasure at his low standard of driving. No, it didn't directly affect me, but this doesn't mean I have to ignore it - where would the world be if we all went round ignoring anything that didn't directly affect us (would you assist someone in trouble or walk by as it didn't affect you??).
The following gestures and remarks were both in reply to his intimidation tactics (beeping and shouting) and also, I must admit, to wind him further up because by that time he was both genuinely amusing me with his complete over-reaction, and also annoying me as he seemed to think he was superior to me (I was just a "f*cking cyclist") and that he was perfectly at right to sail through a red light.
So, I don't class my initial gestures as 'winding him up', but after that they were indeed so.
Yes, it could have all gone pear shaped, but I'll obviously have to deal with that if and when it happens - I will not be silenced just because of the thought that someone may violently disagree with me.