"Refused" is IMHO opinion far more loaded than merely "offering an observation", but we'll have to differ on that one then.
I agree on the cameras, although I offer you this (entirely real - call it Sod's Law) situation. Entirely real as in an analogous situation has happened in my experience. You know you are in the right, but the bit that exonerates you is just out-of-shot.
Cam up all the armed rozzers. I guarantee that (given enough incidents), the critical bit of footage will be missing, as the crucial "action" will be just out of view / off cam / obscured.
Please tell me that you would give the rozzer the benefit of the doubt, rather than accuse him/her of deliberately "just missing" the shot, for want of a better word?
(rushing this post, as in the office!)