An alternate possibility. My wife's Accent gets driven the same path to her work and back every day. Her right front tire (only one on the car affected) is worn on the outer right shoulder. All suspension checks done, everything is tight and right. Rode to the dump with her one day, and it was closed. She took the gravel turn-around (a left hand turn) like she was driving a rally. Then it hit me. The path she drives to work and back is all left hand turns, and she drives a little aggressive. She's always diving onto that outside edge of that pass front tire. Thus the extra wear on that side.
My point is that if this tire was a little low (not flat), and someone turned aggressively where that tire would roll over a bit (maybe an emergency maneuver), it could have worn the sidewall on just the one side, then stood back up and been okay.
Just a thought. Feel free to correct my line of thought. Lol.