Unitary-executive-brain likely means a lot of people won't recognize that this is a big deal. But, it is a BIG deal. Without DOJ independence, it can be used entirely as a very powerful political weapon by a President.
FWIW, I think the entire opinion makes sense if you start from his perversion of Washington's comment on revenge, and assume all the 5 men REALLY BELIEVE Trump's lies about this being revenge.