>Can they say that Newspapers that are owned by corporations don't have complete freedom to publish what they want? Let's say they passed a law saying no corporate political speech within 1 month of an election - would that mean no New York Times endorsements?

Yes, that's exactly what it means! We do the same thing with unions, and with religious organizations that are tax-exempt. What makes corporations so special?

You are, of course, always free to decline the privileges granted to a corporation. Draw up some contracts between you and your partners and write whatever you want, whenever you want. If your newspaper is guilty of libel, you may be liable for that. If your newspaper goes bankrupt and owes money all over town, you might be on the hook for it personally. Accept that in the course of securing privileges natural persons do not enjoy, your corporation may be asked to give up rights that natural persons possess.

Much like patents and copyright, corporations are a legal fiction, invented by society, for the benefit of society. On all three counts, the balance of power has shifted heavily in favor of patent holders, copyright holders, and corporations. This does not indicate some natural law, but rather corruption in our own governments.