How do you know recruiters lie?
The recruiter's job is simply to get the recruit to join. After that, he will never see that recruit again. As a result, it's sad but true that some recruiters (not all) will flat-out lie to a recruit. Whatever happens to the recruit down the road doesn't matter, because he has already improved the recruiter's numbers.
That being said, I still find it hard to believe that any Army recruiter would guarantee a recruit that he would never see combat as a soldier. That's so much of a stretch as to be ludicrous. And given the fact that we are hearing this from Ms. Niederer, who we know is a Code Pink sympathizer and not very stable at the moment, I don't find it that trustworthy.