No, enough 160 bits for finding a private key of address. It's ≈100% probability
Discussion
Bitcoin address is 160 bit hash of public key (which 256 bits). But same 160 bit hash can have many (2^(256-160)) variants of public key.
Judging by the text - yes, it says about finding a certain private key. But I think the meaning meant finding the private key for a certain bitcoin address. And here the probabilities will be different (as written above)