During the old murder case, one of the police had planted a bloody hammer so the prosecution would have a murder weapon -- the box Endeavor found had the real hammer in it. So Thursday was relieved to know he didn't hang the wrong man, but he knew all his past police work would be tainted if it became known that evidence had once been planted.
Thursday is just so sad. He has to work for a thug, his wife is chronically depressed, his relationship with his daughter is strained. The fedora.
On the other hand, when the horrible photographer started talking about one of the little girls as "sugar and spice," I was saying, "Punch him Thursday!" and was not disappointed.
This remains one of the most beautifully filmed, compelling shows, I don't even care if I lose the plot, just watching Endeavor walk through that field after the white horse was wonderful.