While I agree with you, its worth noting that newborns do exhibit a walking reflex (that usually disappears after a few weeks). I would not completely rule out the possibility of a newborn walking with an exoskeleton -- the problem seems to be that their muscles cannot support weight or balance.

Cheesy example video, but the first after a quick search: http://www.youtube.com/watch?v=mJIcKkxx7wg

Edit: and now I see that someone has already mentioned this in the other comments.