Sensors that indicate "not ready" - means that he has to drive a bit more to trigger enough drive cycles to set those sensors. This is part of the I/M readiness system - most places do a quick I/M readiness check for emissions, meaning they plug in a scanner and verify that the I/M readiness sensors are all set to "ready". If any come back as "not ready" or failed (ie, check engine light or pending DTC) - then you automatically fail emissions testing.
Has he recently scanned the ECM, reset a CEL? Disconnected the battery for any reason? Did any electrical work, replaced any fuses, relays?
Basically he has to drive around until those sensors do a self-check. Could be a couple of miles, could be a couple of hundred miles. All boils down to drive cycles - the number of cold starts, cruising speed, duration of run time, etc.
A little weird that it is just these particular sensors that are not set to ready, for this year and mileage - catalytic converter should be fine. Oxygen sensor - upstream (pre-cat) is an AFR type sensor, the downstream (post-cat) is a conventional O2 sensor. At this mileage, should not have gone bad, possible it is a wiring issue. But in any of those cases, it would have flagged a DTC or popped on a check engine light.