I understand your post, but that's a little harsh. The guy made a valid point- combat troops are trained one way, law enforcement folks another.
While we should expect infantry types to obey orders, I suspect they would be prone to "imaginative" interpretations of their orders.
This is in no way a slam at the guys who shot up the civilian vehicles in Iraq- they were in a war zone, they had seen/heard of their fellow troops getting attacked by fighters in mufti, and if I had been there I guess I probably would have done the same thing- if I wasn't too busy crying and wetting myself.
I wouldn't want them manning DUI checkpoints.
I'm not suggesting combat soldiers/marines are rabid, foaming-at-the-mouth beasts. I wasn't when I was in, and I don't think the current crop is either.
The training and acculturation of combat troops emphasizes a set of "conflict resolution techniques" that are not appropriate for the civilian environment.
I want our grunts to keep that "mean" edge...and leave LEO stuff to LEO types.
They're coming here for jobs, welfare benefits, and medical care. The will stop coming when it becomes clear that the well is dry.