It takes a special kind of arrogance to assume these scientists (including the ones that peer reviewed the work for publication) aren't aware that "correlation doesn't prove causation". I mean seriously? You really think nobody thought of this incredibly obvious fact you're pointing out? You think the "after accounting for all variables" right there in the summary, means absolutely nothing at all?
As others (like Baloroth below) have pointed out, you clearly HAVEN'T "taken a good look" at the study, and the things they DID control for. Or in other words... you started with a conclusion of your own ("this study is BS"), and didn't even BOTHER looking for supporting facts.
to start with a conclusion and work his way back to find supporting facts
He started with a HYPOTHESIS, and established a method to test it. An intelligent critique of his specific methodology and control factors would require you to actually read the study. But knee-jerk reactions sure are more fun, aren't they?
When you've identified actual factors he hasn't controlled for that might explain the correlation, perhaps you can submit your own paper. I'll be right here holding my breath.