I had a similar conversation with a police officer while I took pictures of a recently burned building that was being renovated. I was singled out by the office because I had my camera pointed in the general direction of the burned out buidling. She told me I could not take pictures of the building because it was being investigated how the fire occured. All the while people were standing next to me taking cell phone photos of the same building.
After I asked that she get a supervisor, she radiod someone and a few minutes later told me I was ok to shoot. Now I will say the ATF was investigating the site, but was not clearly visible in the street I was shooting from. If they had been, I would have at my own discretion not taken photos of the site as I don't want any federal agents photos to be taken and shown publicaly since it might endanger them. But some cops assume things and I would absolutely require any officer, including Lt Dorn to provide me with a specific statute before I would be willing to give up any of my footage or media.
And I am just a hobbyist. Now if the prison were fully staffed and have people incarcerated, I can maybe understand they would not want people filming due to the possiblity of that footage being used for purposes that might pose a threat to the officers or the inmates. But that is clearly not what happened here.
Here's to hoping Lt Dorn ends up scrubbing a few toilets with a toothbrush for giving other corrections officers a bad name in the public eye.