Hi, I am quite new to here so will therefore be dismissed as another 'know all'.
Without knowing the facts, we cannot really judge any of the people involved in this story. For all we know, the car driver could have got out of his car,blocking the escape route of the cyclist forcing them to stop and entered the cyclists 'personal space' in a threatening manner,potentially causing the cyclist to feel threatened for his life/wellbeing so keeping within his right to defend himself,he used a pre-emptive strike to allow himself room to get away from such danger. This is well above board and is within the law.
If indeed,the cyclist did open the door to strike the driver or did so through his window, the only excuse which would get him off was that the driver threatened to shoot/knife them and went to reach into his glove box at which point the cyclist had no chance of escaping and therefore tried to buy himself a bit of extra getaway time because he genuinely feared for his life.
It could be totally different to that and the cyclist is fully to blame, like i say, we don't know the facts.
I write the above having spent 15yrs in the security industry in volatile situations on every shift and whilst not proud of it, I have been arrested on many occasions and yet never charged even though what I had done many people would consider to be very serious offences. It's not what you do,but what you say.
Yes, I am 6' 2,do wear black cycling gear,riding a graphite bike and I am a large build etc but luckily I ride solo.