when retreating from an approach is the one point strength reduction instead of or in addition to the penalty for retreating from reserve.
e.g. a 2 pt infantry is the sole occupant of its location and is blocking one of the approaches, a manuever attack from another approach forces it to retreat. Does it suffer a one point reduction, or is it completely eliminated.
In your example, the 2-strength infantry would only lose one strength point. It isn't retreating from reserve, it is retreating from an approach and so the penalty for retreating from reserve doesn't apply to it.