I'm speculating, but in a road rage case, I can imagine a lot of scenarios where depicting the victim as gracious and forgiving would make the perpetrator look worse. There's no legal principle that sentencing should be reduced if the victim forgives you, after all. Some contemporary coverage I found in a quick search (https://www.nbcnews.com/news/us-news/road-rage-victim-speaks...) indicates he got the maximum sentence.