Not turning the BWC on in the very moment a scenario becomes non-BWC worthy to BWC mandatory is not necessarily a very wrong action (non-action). There's too many situations where it's unreasonable to expect an officer to turn it on, even when it's written in policy.
OTOH, what I read showed this officer was only there due to the fatal accident and not part of the regular off-duty LEOs working the event. These events require a stupid amount of planning and traffic can easily become a cluster if an officer isn't experienced or familiar with the logistics of the event plan. I can safely bet that the officer had no idea of the protocols for players to get around traffic, and probably got all personally bent when an SUV tried going past him, without understanding how easy it is for drivers to not understand which officer is yelling which command at the moment.
If he did actually latch onto the passing vehicle, well that's just dumb and creating your own injurious situation, that would be chalked up as a learning experience for young/rookie officers. It's easy to make other assumptions about the guy, but at the least it's a weak case that just doesn't lend itself to being reasonable/believable. The DA's office might hang onto the charges for a bit just so they don't seem like their giving a famous guy special treatment, but it's pretty doubtful the whole thing doesn't get canned at some point.
I'd bet a hefty amount that this officer never gets assigned to that event in the future, if he ever tries to sign up.