I personally have never had trouble with my gander going after babies. My ganders love babies of any species. My gander Finn tried to rescue a chick after its mother walked off and left it crying in the middle of the run. Zilla, my gander from this year, is currently rooming with a broody hen who has eight chicks and he doesn't bother them at all.
Geese in general are pretty tolerant of babies, and actually new flock members altogether, at least in my experience. However, I have a small, docile breed, so your mileage may vary with other breeds. The gander is very unlikely to bother his own offspring, though. In the wild, geese raise their offspring as pairs. Both the gander and the goose raise, care for, and protect the babies. Ganders are generally very good parents.
So if you're worried about leaving the gosling with its mother because of the gander, don't be

He'll actually help protect it.