This is line coding, often used on wired connections. But reading a hard drive trace isn't quite a wired connection, so the trade-offs are different.

Most notably with line coding when using positive and negative voltages it is quite important for the average voltage to be zero to avoid building up a charge difference. Whitening can often be used if the downside to an imbalance or long runs is much lower. Notably in RF this is often about avoid harmonics with a little bit of symbol timing advantage thrown in.

Whitening doesn't really require encryption though. Weak cypher streams xored into the data work fine. Even a repeated 256 bit string is quite alright.

Whitening using any non trivial encryption key seems weird to me. AES with a key equal to the current offset in ECB mode already feels over-engineerd.