It could be that the zoo purchased multiple white lions, with the thought of keeping 3 (1 male, 2 female), and sending the rest to other zoos.
What I understand from the video posted, is that Gopa belongs to the zoo, as she says Toronto Zoo can take him back whenever they want. But Gopa can breed, as Jungle Cat World is looking for a mate for him.
So far, I'm thinking along the same lines as Cloudedleopard6. Toronto Zoo received at least 4 White Lions (Fintan, Makali, Lemon, and Gopa) with the intention of keeping only 3. The girls and at least 1 boy, which makes sense. If Fintan and Gopa come from different Prides, they would have maybe been friendly with each other as cubs, but as they matured, they would start fighting with each other. Unlike brother, who share responsibly of breeding. Fintan was probably more accepted by the girls over Gopa, therefore he was sent away to form a family elsewhere.
Of course this is all speculations, and I'm hoping one of us can question a keeper about it. Another mystery to be solved.
On a side note, Cloudedleopard6, how'd you like Jungle Cat World? I've been there once last year. Thinking of going again.