If you want to interpret that way then you need to be able to prove that launching the pod was part of the mission.
Not really. I only need to claim it. Everything else follows from the claim.
But the proof is obvious: a dedicated button was installed* in Kirk's very command chair for launching the pod. The jettison was not just part of the mission, it was the
The episode made launching the pod contingent on an emergency condition when Red Alert is called.
To the contrary, the pod could be launched unrelated to any emergency; there even was a totally separate button for it.
It just happens that there would be various ways to get Finney safely out of the pod before the launch, including ordering him out and then waiting to hear from him; sounding red alert which would mean it's Finney's own damn fault if he lingers; or sending a crewman to drag him out. Kirk did not do the first or the third thing, but would not have been negligent had he done the second, equally good thing. Which he did in reality, but not according to the evidence the prosecution presented.
* By "install", I of course mean Kirk or his technician keyed in a command that altered the function of one of the regular buttons, causing the new function to be presented in text next to the button. Kirk often seems to fiddle with those settings, so that the Intercom and Yellow Alert buttons keep switching places...