I don't think there's a risk of impaction since they are soft worms, but since they get so big, so quickly, I think feeding them to a smaller dragon isn't the best idea. And I don't think the worms will bite your dragon, the one only bit me because I was trying to pry it off its little screen/perch thing and it freaked out (this was a full-grown worm, I never had that happen until they were huge). Your dragon will probably snatch it up and kill it before it could even start to react.