They should not be a huge concern, but as very small Crayfish could be nipped at.
The bigger concern is the parents eating the babies, and babies eating babies as well. They will molt pretty frequently, and become possible targets as their shells take time to harden up.
I couldn't believe it would be such a big deal thinking of it from a human perspective, was very surprised, even as well fed babies they can be little monsters. Thinking about how, in a fish tank, they do not have as many places to disperse and hide like they would in a pond or lake.
Babies do what comes naturally which is scavenge all around every where looking for a meal.