I didn't see an actual link to the study anywhere, but TFA at least appears to assume correlation = causation.
No, actually every version of the article I've seen bends over backwards to end off by saying "correlation does not equal causation".
With this kind of a study, which is methodologically weak (participant recall), I don't think one gets uniform results across gender, age, race, and education very darn often. You would get this in a study of cigarette smoking, because the health impacts of smoking are direct and universal.
When one gets a study with a profile that resembles a study on cigarette smoking in its power and statistical profile, it does tend to clear the mind of ancillary explanations. Occam's razor is practically beating the door down. It's not like sugar have never before been suspected as an agent of direct metabolic stress.
If this study holds up, it's a pretty darn big deal no matter how you slice it. Anyone here have a method to detect 5 years of invisible biological aging which is less onerous than giving someone a fifteen minute quiz? No, I didn't think so.