I've realized something I'm not happy about:
They showed Sousa in the dentist's office reading the orders for Peggy Carter's assassination. They made sure we got a good look at those orders as he read them, the same orders we already saw Dottie write down last week. Now, why would they show that scene? If he were a good guy, he'd just say "Hey, Peggy, they want to kill you," and we already knew that, so then the scene would serve no purpose. The only reason that scene would be included is if Sousa's working for Leviathan and now intends to carry out the hit on Peggy. Which is a real bummer, if true.
My read on that scene was that it was to help sell the idea of Sousa coming back around to believing Peggy. Makeing his acceptance seem credible is especially important since he was the one that outed her and was the most stung by her apparant betrayal. He saw with his own eyes a kill order against her made by the enemy, ergo she's telling the truth.
That was my way of thinking as well. Besides Dottie tried to kill Sousa, so I can't agree with Christopher's speculation.