Cool find.
Had the same issue with a friends 2002 Tahoe.
Had to do the "Drive Cycle" to get it to post ready.
Drive Cycle
http://www.obdii.com/drivecycle.html
The step he was missing was the sustained 55 for 5 minutes.
This works. You just have to have a cold vehicle and go through all the steps.
Biggest issue is If the catalyst is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst.