One of them is also the son of the breeding female, if she isn’t allowed to breed chances are he isn’t either. So that only leaves the breeding male. And there is an excess of males.
In all honesty, the program was already on the edge of being doomed for years. The loss of a full breeding lineage in an already genetically impoverished population alongside the loss of one of the few breeding groups might just accelerate the inevitable. It would be nice though if in time Antwerp would redirect their focus on one of the still viable populations (Diana, Roloway, Brazza or L’Hoest) or get something like mangabeys (three programs in dire need of holders), a species of Colobus or Angolan talapoin.