Er, "Space Seed" happened 15 years before TWOK. Jameson's weapons trade happened 45 years before "Too Short a Season." Why would Terrell and Picard, respectively, who were not even there when these events occurred, would have known the exact particulars? So Terrell's never heard of Khan. So what? that doesn't mean Khan was classified info.
That's exactly what I mean. There's a lot of ground between "I declared it from the top of a mountain" and "I killed all the witnesses", and these particular events definitely call for something in the middle.
Kirk and Jameson, respectively, must have made sure that the facts of the matter would
not be evident to future starship captains who are sent on a mission to the respective planets and actually bother to glance at the Starfleet version of wikipedia first. But they need not have lied to their superiors about everything, or even edited their logs all that severely. They could simply have found sympathetic souls among their superiors, people willing to keep a lid on the respective issues. Kirk's crew can't have been the only people in Starfleet who idolized Khan, and many could feel Jameson did the right thing there - correspondingly, such people would feel "the general public" would not appreciate their point of view, and would keep those ignoramuses out of the loop.
Timo Saloniemi