why would you throw it away keeping a daytime AM on the air?

Running it at a loss. Tax write off. They have a certain amount of time, most often 3 years, to do so. Best case scenario, someone will come along and buy it to air what they want like AM 1110, or match it to an FM Translator. Next best, hand in the license save on the energy costs and sell the land under the tower.

The double whammy for AM Daytimers was a) Being a "daytimer" b) The total collapse of brokered radio.

Z