In an article I read Osbourne said, " These prohormones convert to controlled substances in the human body, we're just closing a loophole." It looks like he was specifically thinking of prohormones when he sponsored the bill as there was no other reference to intrinsically active compounds in this or any other piece I've read about the legislation.
I don't believe a congressman or the average person would really care about the distinction between something converting to a controlled substance or acting directly as a controlled substance. The average person on the streets considers steroid use in the same category as heroin use. For example, product A is converted by the body into heroin but product B intrinsically acts like heroin when ingested. All they are hearing is that people, particularly children, have access to heroin over the counter. You can argue until you're blue in the face about the distinction but all they'll hear is that children have OTC access to steroids.
Let's also not forget they'll be thinking of all the horrible steroid side effects. Their children's genitalia shrinking and falling off, ravening 280 lb sixteen year olds ripping schools apart from roid rage and then dying of brain cancer three weeks later. The demise of the pro-hormone market was guaranteed the moment a congressman needed a "no brainer" grass roots issue to make a name for himself, the hero that kept our children off steroids.