Even assuming for the sake of argument, that it is ambiguous and poorly written, it is not the duty of the Supreme Court to legislate and correct Congresses flaws.

But let us step back for a moment and think about whether it is right for us to even judge something based on the intent, as opposed to the actual text of the law. In this end I would like to think back to political discussions you've had with close groups of friends and family. Each and every person sitting around that table will approach it with their own biases. You will have democratics, you will have liberals, you will have Republicans, you will have conservatives, you will have facists, racists, communists, and other political biases in varying degrees.

This group of people, despite their various prejudices and biases, can agree on certain broad concepts "freedom of speech", "exchanges established by the state", etc. The second someone with their biases attempts to qualify that statement (i.e. "freedom of speech but not fire in a crowded theater" or "exchanges established by the state or federal government") you're going to have someone else (with their opposing biases) objecting to that qualification. In the end you are left with a document that says only that which a majority can agree on ("freedom of speech" "exchanges established by the state"). By adding qualifications and interpreting it post hoc you've actually done nothing more than usurped and changed the intent, because the only intent of the law was that which was codified in the actual language.

To put it in context, nine individuals of varying backgrounds on the supreme court could not come to a unanimous decision or an agreement on what these words meant, yet you're arguing that 535 members of congress plus the president wrote down "exchanges established by the state" when they actually meant "exchanges established by the state or federal government." If these 535 members of congress plus the president meant the latter, then it would have been included in the document that was passed by said members.