What's the purpose of electric fan shutoff delay?

[SunSoaked]

My Dakota Digital fan controller allows me to keep the fans running for 30 second, 1,2 minutes after engine is shut off. I have it set at 30 sec but I'm about to switch my Viper alarm to passive mode. In other words, it arms itself 30 seconds after the ign is off and the door closes.
In reality, I doubt the airflow really matters if the engine is off and there's no coolant circulating.
However, I'm guessing if the alarm arms itself and sees a current draw it will set it off or cancel the arming.