This story is complicated, and it cannot really be avoided by zoos. As mentioned before, the zoo was already below standards when the former owner (a medical doctor, who owns two other zoos) bought it. No normal person would have bought it from him, knowing the amount of money that wass needed to bring it to modern standards, so he sold it to the "animal right group" that has no idea of the investment needed, even if it would only be used for rescuing animals. What must be done better?
1) The authorities should have intervened earlier. For political reasons this is often not done in France but there is also the other problem: what to do with the animals if you close a zoo? This could be an important reason for the authorities to keep a low-standard zoo open, they may just hope that things will improve with the years. In my experiences in France, the authorities have too much other work (production animals) to take good care of zoos.
2) The French Zoo Organisation (AFdPZ) should make minimum standards for their membership. The zoos are not critical enough about their colleagues, still not understanding that bad zoos are negative for all zoos. AFdPZ has among its members some very low-standard zoos, an attraction parc where tigers and lions perform in an arena with gladiators, and for a long time some animals trainers that use their animals on markets and for movies. The AFdPZ should have removed Pont Scorff many years ago from membership.
AFdPZ should also work with the authorities on a "screening system", such as countries as the Netherlands and UK have.
3) EAZA should have removed Pont Scorff much earlier from membership, but was possibly not aware of the problems (because the AFdPZ didn't report anything).
Zoos and their associations (AFdPZ, EAZA) cannot close zoos. But they can show that they consider a zoo as below standards by not allowing them membership and by no longer sending such zoos their animals.