Sure, I understand why they're arguing against it. I mean I don't understand the arguments themselves.
If you don't want restrictions on what you're allowed to sell, or how you produce it, or what you put in it, you're making the argument that a consumer has the right to purchase and use whatever they want. But doesn't that argument depend on the "perfect market" where the buyer has full information about what it is they're actually buying?
The hypocrisy is mind boggling. We have warning labels on cigarettes that they cause cancer, and now we have "anti-warning" labels on milk that tell you rBGH hasn't been shown to cause health issues. So for the companies that do want to tell you how they're making their product, the other players are forcing them to disavow the value of their (honest) claims.