I think the "Costco Card" story is BS.
This is directly from the TSA website.
They should have accepted a state issused CCW however, based on the first item on the list.
"Adult passengers 18 and over must show valid identification at the airport checkpoint in order to travel.
Driver's licenses or other state photo identity cards issued by Department of Motor Vehicles (or equivalent)
U.S. passport
U.S. passport card
DHS trusted traveler cards (Global Entry, NEXUS, SENTRI, FAST)
U.S. military ID (active duty or retired military and their dependents, and DoD civilians)
Permanent resident card
Border crossing card
DHS-designated enhanced driver's license
Airline or airport-issued ID (if issued under a TSA-approved security plan)
Federally recognized, tribal-issued photo ID
HSPD-12 PIV card
Foreign government-issued passport
Canadian provincial driver's license or Indian and Northern Affairs Canada card
Transportation worker identification credential"