I wonder if the scientist in question doesn't know of the possibility of confounders, didn't mention them to the reporter, or the reporter just didn't think that was exciting enough to include in the article. It seems just possible that there is something about 1% fat milk drinkers that is different from 2% fat milk drinkers, which causes them to drink 1% fat milk and which also causes them to have longer telomeres. Unfortunately, there is no link to the study, so we can't see what was controlled for. But if I were a betting man I'd bet that most of the difference is caused by other causes than the difference in milk drinking.