While technically you could be right, my answer would still be a No: you can only play Sortie when the battle marker is on the opponent's side of the track. Have fun!
I think the card could and probably should have been clearer, and if it had been worded as you have above that would have been better, especially as where the scoring aspect leads.
It seems counter-intuitive to me, to effectively say Battle Track = 0 is defeated, yet is not counted as losing; caveats are the enemy of clarity in my humble opinion in design terms.
However, you are the designer, so your answer helps and is gratefully received.
I would suggest that this is added to a potential FAQ, since it also applies to 'To The rescue' presumably.