I think that if they purchased them as goslings that they cared for from day one, and were never too wild with them they should be all right. Like every animal it needs to get used to your actions and personality so that it understands how it wants to act when around you.
Granted though I have never raised chinas but I have had geese for the past nine years (since I was 9 years old) and we only ever had two ganders that liked to nip at us and bite if they were brave enough to actually come up usually when we were bent over checking on their hens eggs. Neither of those ganders were raised by us both were purchased as adults and it was both of theirs first breeding season. The next year they seemed much calmer with us and it was only during the breeding season that they had this pugnacious attitude toward us. And the only time I've ever really been bitten and that it hurt is when I need to check on hens sitting on their own eggs and protecting their nest, and again not all of my hens do that some will just put on the show and run as soon as you get too close.
We've raised Africans, American Buffs, Pilgrims, Embdens, Pomeranians and do still continue to raise all but the pilgrims keeping 15-25 geese total every year. The trouble making ganders were the pilgrim and an american buff. We did not get rid of the pilgrims because of his attitude but because the gander was crossing with our embdens which totally ruined our goslings for show for the next 4 years until we had finally gotten rid of every bird that carried his blood in them.
The best you will ever hear is that it just depends on the bird because like people no two are alike and all have a different personality and there is no personality that is distinctive to any breed. I've had quiet africans and loud buffs, it all just depends on the bird. All the answers you get on here are biased because no one's had the same experiences. The best way to find out is to just start out with a couple and see how it goes from there.