Hasrate secures the network. Not just against 51% attacks. Mining is what builds and confirms blocks. The security of the chain is based on proof or work. We are in agreeance. Miners must comply with nodes. Yes. Your mempool is not your node. It's just the memory of your computer set aside to hold unconfirmed transactions. It has nothing to say about what does and doesn't get mined. That would require a concensous change. A hard fork if you will. Something like removing opreturn entirely or rolling back Segwit.