Why?
My experience is that the media will try to interview someone they can equate to the expected stereotypes as some have postulated on above - someone in camo, or someone with poor command of the language, or anyone they can try to use to reflect poorly on us and our cause. So, we want to be polite, have a good command of the facts, and let the other side be rude and disorderly. That's why.
Plus, I know my state Representative and my state Senator. They are on our side, and poor behavior reflects poorly on my, our group, our cause and my congressmen.
The media will never respect us, no matter how polite we are, or how well we speak to the issues. Interviews of the type you describe, all wind up on the cutting room floor.
If they cover this rally at all, they’ll only do so to paint the ugliest picture possible, and to further their leftist agenda.
Follow the President’s lead. Call them what they are to their faces. They’re going to hate us no matter what we say, so we might as well tell them how we really feel.
They want a war - they got one.