1985 Mustang GT, common rust area????

My brother in law is looking for a 85 GT, we found a nice one for $2,900 here in MI. There is no rust in the common areas, however there are two rust holes in the rear c pillar(between the rear side glass and the hatch). its not near the inbound hinges either, it doesnt make any sense to me to rust there, unless maybe it was hit from the rear and it bent the body. Not sure if he should buought and try and repair that or not. The motor's rebuilt and the car runs out nice, interior is immaculate. Maybe he should keep looking.

Thanks,

Keith