What you just described is a miner who is just mining on their own/lottery mining. That's not a bad actor. They also won't receive any payouts from OCEAN if they are only including their own Bitcoin address in the shares they are submitting to OCEAN. They cannot mine with their own address as the only payout for the reward and also submit shares to OCEAN to receive payouts for blocks they don't find. OCEAN would reject them as invalid shares.