As far as I know, I don't think the zoo has even introduced Inuk to Niki and Aurora. its proabably going to be alittle while before there fully introduced
Its not that they don't want them to breed eventually, I think the fence is partly for the reason above and for management purposes
Example...
Lets say Aurora and Inuk breed (Aurora has actually been pregnant before, but she lost the cub in utero)
It would be more flexible if they had the two yards so Aurora and the cubs could be in one yard with Niki and Inuk in the other
It would also help if both girls had cubs becuase each mother and her cubs could have a yard and they could rotate beetween the three Inuk (There is a third maternity yard plus holding)