The proper term for ectotherm inactivity in winter is brumation. I feel they should be allowed to do what they feel at least. I brumate my frogs in winter. It's not hard to do just give them lots of substrate reduce temps and/or shut off lights and allow temps to drop. That's if you want them to brumate. I personally feel it's good for the health of the frog to allow them a period of rest in the winter.