The writers of 'space seed' did try to make Khan look good in several scenes - like the one you quoted in your previous post - which transforms Kirk&co into far right sympathisers - and the one you just quoted.
The writers overreached - said turning of Kirk&co into far right sympathisers.
Khan was a dictator - he conquered hundreds of millions, at least; the wars to end his oppression cost tens of millions of lives; he was a war criminal. In 'space seed', all he did was try to take over the ship of the people who rescued him - by any means necessary, including killing them.
Having a slick tongue does not make one any less of a savage.
In 'the wrath of khan', enterprise, etc. this is more than confirmed.