jtn, they´re highly unlikely to kill goslings, but the aggression toward other birds won´t likely improve either.If a child gets indignant and noisy when they don't get their way do you let them continue to terrorize the household? I say, put your geese in their own area fenced and secure for them and the other birds. If they are at this level of aggression when other birds are around a gosling probably is not the answer unless you want to see them kill the baby. Letting the rooster at them might have ended in the rooster being seriously injured. Geese are larger and stronger and can do pretty serious injury with their bills. You may want to go ahead and have them for dinner and give up on the whole goose thing.
Mine will grab a chicken or duck tail at feed-time, for example, but soon let go again, and have never hurt any chickens or ducks. But then they´re Pilgrims, very mild.
If someone really loves their geese and wants to keep them, there´s always a way to be found, but sometimes it´s just easier for others to give up on the idea, as you said. And devella didn´t actually go out to get them, they were given to them. I´m enchanted with my geese, but not everyone feels the same way, eh? Each to his own, as they say.