We too just got a chinese snow goose out at thebunny sanctuary where I volunteer. No babies though but Gus seems to be a mean old boy.

I have no idea why mom would be so mean to her baby.....except that maybe she thinks it isn't strong enough to survive. I'd continue to keep the baby away from her until the baby is quite a bit bigger....then I would still watch her closely. You may never be able to have them be together if she is a stubborn bird.