Which encrypts each cache line with a key unknown to the attacker. This means an attacker can't target individual bits. Every change affects at least one AES encrypted block. It's much stronger than any normal defence against row hammer in that regard because flipping a single bit in plaintext changes ~half the bits in the ciphertext. It's similar to how Apple uses always on disk encryption instead of the normal means to limit run length in their NAND flash controllers. If the encryption is "off" it just means the decryption key is stored somewhere in the trusted enclave.