There's two different types of Standby with DL. One is standby, as in you're not confirmed on the flight and are on standby to get confirmed on it. The other is standby for a seat assignment. If his BP says SEAT ASSIGNMENT REQUESTED, then he's confirmed on the flight, but needs to be assigned a seat. If his BP instead says STANDBY, then he's not confirmed on the flight and must be confirmed before he can get a seat assignment. This causes confusion because the display doesn't make clear which type of standby each passenger is.