I watched this episode just recently.
Wow.
What a glaring mistake. McGivers was not very believable. I mean seriously... I understand her idealization of prominent strong men from earlier centuries, but c'mon. Khan demands her support because he wishes to take over the ship. TAKE OVER THE SHIP. Sure, she can be infatuated, but to give into him so easily? She wasn't surprised at all...
[snip]
There were quite a few glaring mistakes in this episode. Ummmm... remember "Mirror, Mirror"? If someone uses the transporter, a status light flashes on the helmsman's security panel. So... what, there's usage of the transporters to send Khan over to this ship them beam his crew back over to the Enterprise, with no one knowing about it?
[snip]
And finally, in the end... Kirk seems to show this "curious respect" for Khan, giving him a chance to build a new world. I'm sorry, once a tyrant always a tyrant. What kind of "experiment" did Kirk think he'd "try out" like this? No... this was not aligned to the way Starfleet operates. And McGivers would have been courtmartialed. No two ways about it.