In restrospect he dealt with the Khan situation badly.
Why does Kirk have to shoulder all of the blame for what happened to Khan and his people? Reports and logs were filed with Starfleet Command, it wasn't like Kirk was the only one that knew they were left on Ceti Alpha 5 with a limited amount of supplies. Why was it his sole responsibility to check on their progress? Spock, McCoy, and about 400 other Enterprise crew also knew what happened, none of them ever were curious enough to follow up and ask a few questions for themselves?
There isn't some Federation department or bureau that tracks and monitors colonies and settlements? And over the course of 15 years, no other ship ever visited that system and noticed that one of it's planets was missing? There was no mention of Khan or the Botany Bay in the database entry for Ceti Alpha 5, or vice-versa?