I'm suspicious of this sort of research for lots of reasons, but concerns about the direction of causality is pretty low on my list in this case.
Poor decision making skills. Excepting possibly neck pain (and even then I could work it in), that could underlie them all, and there's a certain amount of evidence to suggest things like willpower and discipline exist as at least statistically-distinct entities, even if you can't quite point at the willpower organ.
In this particular case, it's easy to imagine how a long commute could cause obesity, divorce, and neck pain; it's very hard to imagine how the causality could run the other way, or what a common cause might be.
The rule could stand to be taken with a grain of common sense.
Correlation != causation.
It is not right either. It is just boring.
Correlation is a starting point, not an ending point.
On the contrary, a (mind that: possible) common cause is even suggested in the article itself: "Perhaps long-distance commuters tend to be poorer or less educated, both conditions that make divorce more common."