Sorry. Been away for a bit. As one of the resident legal beagles here at APS, I'll throw in my two cents on the charges here. The piling on is the prosecution putting alternate charges in front of the jury. Kind of saying "if not Charge A, consider Charge B or C". When the jury deliberated, they can find guilty of all, none, or some of the charges. When the jury finds guilty of multiple charges, as happened here, the judge will then merge charges and/or vacate charges, depending on how they overlap. If you listen to the sentencing, the judge vacated a lot of the charges by operation of law because of the conviction of the one murder charge. The "lesser" murder charges got kicked by the judge. The merger applied on some, where the conviction of the higher charge incorporated the lower charge (often see this in Burglary cases, where a theft charge ends up merged into the Burglary at sentencing). The "problem", if you will, is that prosecutors any more throw any possible charge at a situation, to either give negotiating room for plea bargaining or to give them more chance of getting a conviction at trial. I blame this on prosecutors who keep conviction stats of their staff and use that for promotions, pay raises, etc. But, since conviction rates get brought up so often in elections, I guess that matters to the public. In my opinion, if plea bargaining went away, prosecutors had to open their file (more or less) in the discovery process, you would have charges based only on what actually happened, eliminate this stacking of charges, and there would be better results for both sides.
As for the felony murder rule, my understanding is that this guy wasn't just there. He was actively pursuing Arbury, and worked to get him cornered between the two vehicles. In other words, he did an affirmative act in commission of the felony (Unlawful Arrest/Detaining) that resulted in the death.
IMHO, this case was correctly prosecuted and sentenced, given the facts of the case as I understand them.