No, because that would be another public blockchain.
Private really means what you think it is "a blockchain that only a small selected group can access". A lot of "Private blockchains" are just Ethereum-nodes running behind a firewall and with a secret genesis-block.
It does not, however, mean that it cannot be peer-reviewed. Allthough that still leaves the problem of not knowing if what you've reviewed is what is running.
Private really means what you think it is "a blockchain that only a small selected group can access". A lot of "Private blockchains" are just Ethereum-nodes running behind a firewall and with a secret genesis-block.
It does not, however, mean that it cannot be peer-reviewed. Allthough that still leaves the problem of not knowing if what you've reviewed is what is running.