I thought it was Liberty trying to fix the engine sound debacle. You know, Super Bowl and all...
Being on the world feed that narrows it down quite a bit. They don't have commentary during the race so it's likely an ambient mic from around the track. It was a helo shot so they wouldn't have been using a mic from up there. The comms, talkback and IFB sends route through the console on live TV shoots particularly sports. That could mean it was someone clowning about on the crew, talent, etc but those things are routed through the desk differently than a program feed. Plus that would be pretty much game over for your gig if you got caught doing that on purpose and maybe even if it was an honest mistake.
My guess would be it's an ambient mic somewhere that a person could get to it and talk or shout into it pretty easily. Could have been a corner worker. My understanding is not all down there are licensed SCCA corner workers. The region doesn't have enough, they can't get enough to travel down there (they volunteer and pay their own way) and I understand some of the spots have more inexperienced workers. When we do gigs that require ambient/crowd mics we try to place them so they are close enough to get what we want but positioned so a) nobody steals them b) nobody in particular can be individually heard in any particular mic especially when it's live.