Really? I don't get that. The reason that people use the word as an insult is because it is a word used to describe people who have intellectual challenges. It doesn't matter what you do, the euphemism treadmill will get you in the end. As evidence I submit this anecdote: I was spending some time with a couple of young gentlmen (kids of a friend of mine) who are 9 and 11 years old. Big kid was teasing little kid, so big kid said "you're a special needs kid!". Does this help you see the futility of rotating in new acceptable terms every couple of decades?

The Time Agents from the 51st Century (of whom Captain Jack is one) were actually first mentioned in the classic Tom Baker story "The Talons of Weng Chiang". Robert Holmes was the author.

I'd love to know where Jack was when the Doctor was "with the Filipino army at the final advance on Reykjavik", as he states in that story.

And you wonder why the rest of the world sneers...