Why would you run a chiller loop at a temperature where you need anti-freeze? That would be extremely inefficient, cold water is cold enough for a heatpump chiller. Though I doubt they are even using a heatpump, it's probably just air cooling, with a water loop to get increased surface area where needed.
Air-cooled chillers sit outside and are not always turned on. Depending on the design conditions (climate), you can either add glycol to the chilled water loop, or you can apply heat trace to the exposed piping. I'd wager that glycol is rare in a chilled water loop and that heat trace is the dominant solution.
Water-cooled chillers will sit inside and require a secondary loop for their heat rejection. In the non-evaporative case (a la Microsoft's marketing here) you're using drycoolers. Again, not all drycoolers will be on all the time, and the same considerations apply - how do you prevent freezing. It's more common to see glycol on external loops to drycoolers.
So to your question, it's not about the temperature of a "chiller loop." It's about the pipe segments and equipment that are exposed to the environment that may have non-moving water in them.
I promise you, ever single thing you can think of on how to design these systems has been thought of and tried. If some sites have glycol in them - and some do - there was thought put into that decision, and someone weighed the pros and cons and made that call.
