Assuming that OCEAN runs a BIP-110 node (fair assumption) for broadcasting, it would view the block as invalid. But because of the way that DATUM works, you would still broadcast your own block and if POW is correct, it would be accepted by all NON-BIP110 nodes.

As far as "Offical Announcements" OCEAN is simply organizing hash. Shares are not tied to transactions on DATUM(how could they be?) So, you still get shares for POW and still get block rewards. You building blocks, and the transactions you include are your business but, if you don't mine a valid block, a pool can't really DO anything about that.

For a STRATUM connection, yeah, that's the whole point of a pool. A collective building a shared template together (which wouldn't allow invalid transactions) so if your mempool tried to include an invalid transaction, it would be rejected.

As for Profitability, the subsidy is orders of magnitude higher than all fees combined for inscriptions, large OP_RETURNs, and taproot tapscript transactions. So this is just burning dollars to pick up pennies, logic.