What Gammons missed (and most of the news media that reported on it, for that matter) is that Rodriguez clearly never admitted to using steroids. His choice of words was Clinton-esque. He never wanted that sound bite in which he spoke the word "steroids" to put in the time capsule -- a manufacturing of the truth that created the clumsiness.
So we got Rodriguez first telling us he used "a banned substance," then saying "I don't know exactly what, um, substance I was guilty of using," and then going to the plural and saying, "I started experimenting with things that today are not legal." So what he is saying is that this fitness freak took something or some things for three years and didn't know what they were, but even though he didn't know what they were, he somehow knows that they were banned.