Well they already chose Swift over Rust because they said:

> Swift is strictly better in OO support and C++ interop

So I guess from their point of view that’s why not rust.

I don’t have a horse in the race.

I was genuinely interested in why they didn’t even consider D given they already ruled out rust for those particular reasons, for which it seems D would fulfill nicely.

It is not backward compatible, the library system is immature, and there is no variety of different compilers for the language.