The name comes with the religion, not the ethnicity.
This is another weak dodge of a kind we've already seen multiple times in this very thread. The religion is overwhelmingly identified with the ethnicity and we all know that, okay? Can we please just dispense with the constantly-revolving carousel of evasive bull?
If you choose as a fan to rationalize it in this or that way then cool, whatever works for you. Certainly it's possible for many things to happen to race and ethnicity and the fortunes of names. But you don't get on the strength of any such rather tenuous fanwank to pretend that Khan was not originally sold as an exotic Asian character, or to tell other people that they're unreasonable to make the connection to that concept, or to claim that whitewashing is irrelevant. I think that's something you're just going to have to come to terms with.
IOW, rationalize things as you please, just don't be a dick about it.
King Daniel Into Darkness wrote:
And when Noonien Soong turned out to be a white American in TNG...?
Also a bit odd, TBH, but at least that wasn't a character who'd already been established onscreen with a specifically Asian backstory, so there it's easier to pass over the name-ethnicity combination as a mere oddity. It doesn't attract the same attention as the conspicuous transformation of Khan for that reason.
Taking a cue from that, now for something completely different
and hopefully a little more interesting than circular bickering about Benedict and Khan:
contains something I did not know about the name "Noonien Singh" and why it turned up in two different versions in Trek: apparently the name was a reference to a real-life friend of his named Kim Noonien Singh
The article ultimately pulls the claim from IMDB and I don't know how credible it is, but surely this would be the place to find someone who can verify it?