It really does just come from this inchoate sense, derived from the film 300 and half-remembered high school history, that the Spartans were the most manly men to have ever manned and that's it. It is that thick-headed and anti-intellectual. There is no grappling with the actual Sparta.
I am endlessly fascinated by right wingers' obsession with Sparta. I can understand an initial vibes based appeal I guess - like if you opened the first page of a book on timocracy and were twelve. but the thing about history is you can find out what happened to those guys