Is it insulting when the media shows the Dallas police sniper in his military uniform?

"The media", in the case of which we are discussing here, is a visual medium. Unlike radio or word-of-mouth, visual aids are used as part of the story that is being told. TV, newspapers and the various internet news sites need something to show to accompany the story. When a search for a photo of a person making news is found, it could be from a drivers license, a high school or college year book or some social media source. If the person about whom the story is being told does not drive, or maybe didn't finish high school, news sources will seek out photos where they can. If the person of note happens to have been in the military, it might turn out that a photo of he/she in uniform is the picture they use. In the Dallas situation it turned out the person of note had served in the military. Let's say, for the sake of argument. the only photos of the subject were from Boy Scouts, being an altar server or, even...cosplay. If you were the editor, would you use those pictures?