Of course he voted against it.
How can the market work in his "libertarian" proponents' favor if people have the information to make a free market function.
If people want their food products certified in a certain way and are willing to pay what it costs then the market will provide this service. These laws are both redundant and an infringement on property rights. This is Ron Paul's perspective and I totally agree with his vote.
Sorry that's doing it backwards. If you are being sold something, you deserve to be told what's in it. You are free not to read it, but that is your choice. If the product does not have facts that you need to know on the packaging, you never get the chance to make that choice.
So why is it "backwards"? The market already solves the problem. You haven't actually made a counter argument, just restated your case. People will have labels if they are willing to pay the premium for labels. If they aren't willing to pay the cost, then what's the point in forcing them to pay for something that they don't want?
Why are you "free not to read it"? If you don't have the facts that you need to know on the packaging, you never get the chance to make that choice. The only solution is to use the states monopoly of violence to force people to read the labels, right? People are also free to not buy a product without a label on it. On one side you advocate personal responsibility and on the other hand you advocate coercion by the state.