Suppose that a miner find the right hashes but involuntarily or by malicious intention then create an invalid block, like trying to double spend a transaction
My guess is that the moment this block is broadcast the first node to receive and test this block will immediately copy the correct hashes and produce a block of his own this one valid and with his own coinbase address.
I know that this scenario has little chance to happen because miner know that their coinbase will be steal and rejected by the network, but is this a valid working process ?