Yes, yes you are.
For one thing the BBC story only said " the moped had been involved in a crash with a car" and you automatically decide that he hit the car and rode off with no basis at all to reach that conclusion.
Every other report says the car rammed his moped. And according to the latest ITV report the police say that “Everything that we have learned about this attack so far indicates it was targeted and intent on lethal force from the outset.”
Aside from his riding illegally I have not seen anything to suggest any wrong doing on his part to cause what happened. Nor is it even clear if they literally do mean a moped, as in the legal definition, rather than a scooter.
So to jump to all the conclusions you did, to consider it perfectly reasonable to make those assumptions — that if they stabbed him that he must be the bad guy and they must have been entirely innocent and provoked into doing so — and to think it acceptable to assault him, then yes. Those things definitely make you horrible.