Aurora GPS RWY 17 Question

The GPS RWY 17 approach at Aurora State (UAO), Aurora, Oregon, contains a
note near the top left:

http://www.airnav.com/depart?http://...4/05722R17.PDF

"Procedure NA for arrivals at UBG VOR/DME on airway radials 013 CW 085."

There are two Victor airways to UBG, one on the 013 radial and the other on
the 085 radial.

What exactly does that note mean and why is that an issue? It sounds like
the note prohibits use of this approach if you are arriving from the
northeast (between the UBG 013 and 085 radials). But I can't see any
obstruction issue or interference with another airport's traffic pattern,
since the minimum altitude is 4,000' in an area near sea level. If you
overflew UBG for 5 miles and then turned back to UBG, would that make the
approach legal to fly?

Dennis Johnson