1. English transliteration has its own cultural inertia. It's not just about what's most phonetically sensible (that too only for some particular English region: how an American phonetizes non would be different from how a Brit or Aussie would).

2. Don't assume the Uzbeks say this word the same way as the Indians do. It may very well sound closer to "non" in Uzbekistan.

Uzbeks do say "non".