It seems to me that the plot is set in motion by Flint trying to do what he said he was trying to do: put Kirk and Rayna together so that he, Flint, could then take over in a new role as her romantic partner. Of course this was a poorly thought out idea and worked out badly, but how could it not have been poorly thought out? Either Flint had little time (once the approach of the Enterprise was detected) to hatch this idea, OR he'd always had such a plan in mind and simply thought a visit from a Federation ship with a youthful captain - one who, moreover, knew how to get close quickly to human/humanoid women, and who frequently desired to do just that - was sooner or later inevitable. The latter idea seems implausible: What if acne-scarred Captain Tracy's ship had happened to arrive at his planet first, or the Vulcan-crewed Intrepid from "The Immunity Syndrome"?