My husband feels, and apparently so do some other people from other forums, that biting should never be tolerated.
We won't pull mothers from babies, but biting can be an indication of aggression, which is an undesirable trait. We tend to feed off anything that displays traits we don't want becoming more common in our feeder population.
The Earth is the cradle of mankind, but one cannot live in the cradle forever. -Konstantin Tsiolkovsky