I didn't read the study, but I'm a bit skeptical the issue is "less energy is going to fight cancer". More likely, higher metabolism a are correlated with cancer. Colder weather = higher metabolism = higher oxidative stress on the body.
Consider the flip side that rats who live close to starvation tend to outlive their well fed counterparts.
That's what I would expect too.
The other example isn't really a "flip" side, its the same issue - restricted calories leads to slower metabolism, which means slower cell aging and cell growth which means it takes longer for the telomeres to run out. Once telomeres run out, continued cell division starts causing random mutations. A random mutation which stops the cells mechanism to know when to
stop reproducing is cancer (the cell just keeps growing past the point of self-replacement, indefinitely).
So, moving as little as possible, and eating as little as possible, would presumably not only combat cancer, but slow all forms of aging.
But of course, lack of exercise also
causes all sorts of disease.
The health detriments of not exercising seem to outweigh the benefits of slower metabolism, so there is really no good reason to try to apply any of this to real life.