Very well.
Citizens United Holding:
The 1st Amendment of the United States of America:
Notice how, in that wording nowhere does it say 'For American Citizens' or anything similar. It simply says that Congress is prohibited from passing any laws that abridge 'freedom of speech, or of the press'. The First Amendment is phrased as a general limitations on government power, not special protections for a specific class of people.
The law apparently disagrees with your interpretation. So, file suit & take it to the SCOTUS.