AFAIK the cam deliberately switches to B&W mode when IR is turned on. Retracting the IR cut filter changes the colours somewhat, but I personally would prefer to see colour as it can be an important bit of evidence.
I agree there's no reason to switch to black and white. I suppose the thinking is that colors are distorted (sometimes greatly) in IR mode, but so are black and white. I have dark clothing that appears almost white when the camera is using IR. And I've seen object go the other way, as well. That context may need to be presented along with the camera evidence regardless of whether the video is color or B&W.