Oh, are the Koch brothers journalists now?
They do contribute funding to journalism. The publishers of The Nation are also a corporation and attempts to influence the results of elections. It's hard to find a clear division between the press and political advertising. Certainly none existed during the period when the First Amendment was written. Newspapers were partisan or factional documents, and political communications - other than what was spoken directly - literally were printed on a press. Freedom of the Press isn't limited to what Congress decides is objective journalism.
I agree, and it would probably make any acts passed subject to a new round of court challenges. Any wealthy activist could still buy a media company, even a small one, and use it to push a political agenda. I could also imagine that a law might allow unlimited individual expenditures under the banner of free speech, and the distinction between types of legal persons makes me think that would be a likely outcome. This would close the current sources of funding, but as long as individual speech and press freedoms are maintained, there will be a pathway for money to weigh in on politics.