Earlier quoted context omitted.
It's optimal IMO. Anything shorter is too ambiguous, anything longer is longer than it needs to be.
You think "SF" is ambiguous compared to SFO?
Science Fiction being a big one.
There's Santa Fe, CDMX though. You may have decided that Santa Fe, NM is too small, but you may not have considered that one.
People don't normally call that SF though - but they could. And that's why SF ought to have a more narrow use than SFO.