Back during the Michael Brown shooting I remember reading that the officer shot the suspect six times, with numerous sources claiming the weapon was a revolver. I'd imagine many reporters equated "6" with "revolver". Who knows though?
As for the Madison incident, I'd imagine the reporter just used revolver as they didn't know any better. It said in the video that the officer was a 12 year veteran, meaning they probably joined the dept back in 2003. I highly doubt that even back then the Madison PD still issued revolvers, so it's unlikely he was somehow grandfathered in before semi auto adoption.
Not saying it's impossible, but I'm not going to go off one reporters words. I don't think you could find a single police officer in America still carrying a revolver who hasn't been in for 20 years or more.