i don't think removing OP_RETURN was being proposed, though i personally think segwit should be deprecated and OP_RETURN should be hard limited in the consensus to 80 bytes. i also think that there should be a variant of P2PKH that uses schnorr signatures and 256 bit address hashes for the more common single-signer schnorr signature transactions (so, P2SPKH) because taproot by default reveals the pubkey before spend for reasons.

changes that touch the consensus are much harder to achieve anyway, but you can promote mempool filter rule changes that become popular and impede abuse that exploits it by slowing down propagataion.

idk why anyone would want to use core 30 unless it actually adds features instead of removing them. limiting users ability to participate in the selection of mempool submissions is not ok.