The modulator monitors wheel speed at all times I believe, since its essentially an abs modulator it senses that wheel is moving a different speed so it could possibly think there is any issue with the sensor and trigger a code.
Will it stop you from getting back to the truck? No, but it's just something else to have to deal with if it triggers a code. Not to mention what else it could cause mechanically in the diff.
I know on the P1K LE you can monitor every wheel sensor individually even in turf mode using our diagnostics computer. I'd assume in turf mode the PCM is told to ignore the difference in wheel speed on the rear since they are unlocked. But something is watching them, the Talon won't allow us to view the individual front wheel speeds though.