If I was in charge of a police department I would never spec road bikes for my cops. Mountain bikes are much tougher, less fatiguing to spend time on, better visibility and vision, less expensive, and 9/10 as fast in a pursuit situation. If you lean down and have good tires, it's basically a draw.
Modern road bikes are artifacts of building a marketplace on the image of professional racers. I love them, as do many others here I'm sure, but what matters is the rider. I've had the experience of passing a paceline on a mountain bike. I've had the experience of leading a fast paceline and getting passed by someone else on a mountain bike. Both are exciting!