AGM is a funny animal. Even when discharged to 8-volts, the saturated mat still contains acid in the 1.180 - 1.190 range. Why? AGM batteries start out with a 1.300 electrolyte density and fall on their face with a denser gravity than a flooded battery.
I would not like to experience a day that could freeze an AGM battery even when the battery has been reasonably flattened. "Reasonably" means a constant load has not existed for weeks utterly exhausting the battery.
Internal plate (grid) and separator structure of a quality GC battery is far stronger than it is for a car jar battery. Meaning the plates are more bend resistant. But this increased strength only goes so far. It should not be construed as any type of "advantage" but rather as a reason why golf car batteries seem to survive freezes "better" than a car jar RV battery. But please don't extrapolate this as being a tangible "advantage".