Although this statement is more or less true, it is not true in the same way it is for BPs. Most BPs have excellent temperament from the second they hatch until they die. I've even seen plenty of people talking about taking a mother off her eggs and she only hissed.
Most colubrids are spastic as hatchlings, which can make them a little difficult to handle by the time you consider how delicate the little things are. They may bite and/or musk. They rattle their tails, which to some is quite intimidating.