I have had a handful of different pets throughout my lifetime, and as far as danger to children I think only my fish and corn snakes are less of a threat, and maybe my little turtle that I only had for a few months as a young kid.
Dogs, cats, rats, hamsters, ferrets, iguana are all more likely to actually cause any real injury to a young child.
Of course, I'm not going to 100% guarantee a BP will not strike or potentially constrict a young child. Of course, its possible. The likelihood of a BP causing any significant damage is VERY slim, however.
With proper adult supervision a minor bite would most likely be the biggest threat. An adult BP could potentially constrict enough to cause serious injury, but it would take some time and is probably as likely as hitting the lotto. If supervised, and the huge long shot occurred that a BP actually constricted with the intention of "killing it's prey" an adult would easily be able to intervene and prevent such an injury.