Isn't there a room issue with the rhinos there? I expect Zuri will move on in a few years so thy can breed from the mother again.
I think they could keep three at a pinch- the inside has two exhibit stalls-similar to Tsavo, there is a decent sized double yard and a 'summer' paddock. Its not huge but could (borderline) hold 3.
Another alternative would be for them to keep the two females and have a bull just visit for breeding purposes as Kingo has already done. But sending Zuri away and having a 1.1. pair again is probablty the most likely outcome.