Join Date: Apr 2009
Location: Bye Delta
Programs: AA EXP, UA Silver, HH Diamond, IHG Plat, Hyatt Plat, Marriott Titanium, Nat'l EE, Avis PC, Hertz PC
Posts: 16,630
Not Valid For Travel sounds like an itinerary document, not a boarding pass.
Did they give him more than one document at check in? Did the boarding pass have a ticket number (not a stock control number… both start with 001)? Did it say anything like Flight Coupon Req?