Reintroduction is not the same thing; that’s an attempt to reverse our damage and restore the ecology that existing before we fucked shit up.

There’s definitely a potential for negative consequences, once the balance has been damaged long enough, but wolves inhabited Yellowstone for hundreds of millennia and have only been gone ~0.03% as long. The years of planning were probably regulatory and because wolves are complex social animals that can’t simply be abducted, dumped, and expected to succeed as though you didn’t just traumatize them with teleportation.