Why? Leftists seem to get nothing but fawning, groveling subservience from legislators, and all they do is scream at them.
Let the puke politicians earn our respect, by serving our interests for a change.
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.