I have given my larger (animal protein-eating) tortoises hard boiled eggs still in the shell, but I wouldn't give them to babies. The shell might harm their tender throat tissue. You can get calcium in much easier form for the babies. Even a cuttle bone would be better than egg shells.
I wouldn't do it. There are other better ways to get calcium in to them. Seems risky from a bacteriological standpoint. I only feed eggs and egg shells to egg eaters, like my monitor lizards. They are naturally equipped to deal with the sharp edges and the present flora and fauna.