That sounds like a crap apology to be honest. Just covering his back.
Essentially it was a forced apology. The van driver had no way of knowing if the OP would still contact the police and use it against him if he gave an unreserved apology.
So yeah he was totally covering his back and probably thought a token apology would be the best way to keep him from dealing with the police.
The van driver should count himself lucky, not only could he have seriously hurt someone he then went on the offensive. Well done to the OP for remaining calm.
In some respects I think the email was the decent thing to do, on the other hand if the van driver was reported to the police and had to deal with that situation he might be more inclined to think twice. Who knows.
Either way, it was dealt with and dealt with well.