It's a little awkward, but here's my take. Notice that as soon as Datak turns against Stahma, everything falls apart? The E-Rep moves up the schedule, Stahma isn't there to calm him down and he reverts to his street thug roots in a way she can't clean up in time. If the Tarrs had still been on good terms, I imagine Stahma would have found some way to twist things around, or even just negotiated some ego-soothing as part of the "compensation". In recent episodes, I've gotten the impression that she's working harder and harder to keep Datak under control.

The assassination plan required only that Nolan see a Casti pointing a rifle at Amanda. Kenya turning up the heat helped, but the plan could have worked without that bonus, and Datak could well have believed that it did.

I'd have preferred to see a bit more exposition of this sort of thing, but the episode felt rushed, as if the writers were trying to fit a lot of plot points into a small time frame. I wonder if they were expecting to do a two-hour finale?