They do mention they are a smaller station, and don't mention any of their equipment being used.... but generally speaking.... somebody should have noticed the INSTANT the AM side of things wasn't broadcasting. Usually, there are monitors in place to ensure each transmitter is a) operating and b) operating within the guidelines of the FCC. Back in the day, most radio boards had a "Modulation" meter to literally show the modulations of the waves you're outputting. If that sucker be sitting at ZERO.... you're not broadcasting. Used to be both the engineer AND the jockey either had their own modulation meter or both of them could see one.

Some larger stations have the budget to point cameras at the broadcasting equipment so that people could log in remotely and have a look at transmitter status.

These guys are either REALLY small-market, or just this side of incompetent. You'd also think that if anybody listened to the AM broadcast, they'd have been curious why it was shut-off without warning. Hell, if the FCC were on the ball, they'd have been asking "Why is this station supposed to be broadcasting over both bands and yet one band is dead?"

If you're licensed to use a particular frequency, you USE it.