If this person is habitually rude, then you are not telling the manager anything he doesn't know. If the person was having a bad day, then you should probably h

If this person is habitually rude, then you are not telling the manager anything he doesn't know. If the person was having a bad day, then you should probably have given him a wide berth and let it be. If the person is a jerk behind the manager's back, then it's up to the manager to sort that out. I don't see it as your job to help him with that. He's unlikely to give too much credence to your feedback anyway, as you are rejecting the offer. People do not take feedback well when it's mixed in with disappointment.