Temperature plays a major role in reproduction, worm casting production, feeding and microbes.
First off, if you look at the worms that have been refrigerated, notice how lethargic they have become. Being they are in this state they either eat very little to nothing at all. If you take some from the same batch and refrigerate some for three weeks and compare to ones that have not, you will notice the difference in their girth. Since they have not eaten, they are not as healthy and will also die much faster on a hook as well as be less active.
When temperatures get too cold, being the worms become lethargic, they also become less prolific. This happens as a result of less activity, not eating enough and worms that are not as healthy. If they are eating less, they are producing a lower volume of worm castings.
Wade, you also have three major types of bacteria when dealing in worm composting. Under 70 degrees Fahrenheit you have Phsychrophilic bacteria which are not very active. At temperatures of 70 to 100 degrees Mesophilic bacteria, the fastest decomposers come to play. The faster your material decomposes the faster your worms can eat it. Also, depending on the type of worms, however between 70 to 85 degrees your worms become most active, eat more, become more prolific and are healthier.
So essentially, if you are keeping your temperatures up to the recommended zones, your worms will be healthier.
This is not to say the ones outside are not in a heated bed do to decomposing matter… I have no idea how your friend is actually raising them. If to many green materials are added you take a chance of making too hot for the worms as well as raising the acidic levels too high.
On another note, the shelf life of a worm in a worm bin can be anywhere from one year to what I have heard, up to ten years, depending on type of worm and the environment. The shelf life of a worm in a refrigerated environment can be 24 hours to three or four weeks depending again on type of worm and the temperature of the refrigeration unit.
The latter paragraph in itself should say something by itself