I dont know the answer to your question but can offer a few points of encouragement. If the worms are active and breeding then there should be some eggs that go dormant over the winter and restart the bin in the spring.

I am guessing the garage gets quite could in PA but maybe there is something you can do for the small area the worms occupy. There is a handy little gadget called a thermo cube that will turn on and off an outlet based on temperature, coupled with a heat lamp it will come on any time the temperature approaches freezing.

I would guess that near freezing could be the better part of winter though so it may not be effective in the open garage but inside of a small insulated box it should be an inexpensive way to keep the worms from going iceage on you.

The box need not even be much, you can get that 2" pink rigid foam at the hardware store. That stuff is easy to cut with a hand saw and a few pieces of duct tape would hold it together also making it easy to take apart come spring for flat storage in the rafters for the warm season.

If you have a regular compost pile and it's big enough, they'll likely disappear into the pile and reappear in spring, then you could restart the bins in spring. Don't know about having them in small bins that might freeze.

If you want to hedge your bets, split some worms out to the regular compost pile, and leave some in the bins, and see how it works.