Leaving them on a barely hospitable planet is one thing. Khan was up to the challenge. Not doing a proper sweep of life forms and their potential dangers, not doing a system study to make sure there weren’t any obvious signs of things like an unstable star or planet, and not making sure someone checked on their status regularly… Kirk totally screwed that all up.

The very fact that when the Reliant showed up to do its research they didn’t realize a planet was missing… Kirk never had them even file the system into Federation databanks!

They didn’t know the sixth planet was unstable!!

“THIS is Ceti Alpha V!”