In all that I've learned, if someone is suffering from pre-, mild, or even early moderate hypothermia, giving them hot, sweetened fluids is a recommended form of treatment. Then followed by more simple carbs. The body needs calories (sugars) in order to produce heat. I agree the warm drink can help the subject's mental state, too. Then more treatment to warm the body core.
Giving warm fluids is not trying to warm up 20 gallons of water with one cup. It's providing calories for metabolism.