The 40,000 miles do not need to be flown on OZ metal flights. "Asiana Flight Miles" is simply the term that OZ uses to describe base (actual) miles flown.
From the Asiana Website:
The more you travel with Asiana or our Star Alliance partners, the quicker you will earn the additional benefits and prestige of an Asiana Club Elite program member. At Asiana, we make it easier for you to qualify for Elite status by allowing you to apply your total accumulated miles from both Asiana and Star Alliance flights towards Elite qualifications from the day you first sign up for the Asiana Club program. And all Class of Service mileage bonuses count towards your Elite qualification thresholds as well. We then go the extra step of making it easier for you to requalify for your Elite status by setting very attainable flight mile goals over a 3 year qualification term, instead of the annual requalification required by most airlines.