Against censorship

Suppose he bought he ads–would groups like CSPI have the right to get an injunction to block them until the courts decided that he was acting “independently”? How would a court decide whether he was acting “independently” or under the auspices of a corporation?

You appear to think that because corporations get limited liability protections, you have the right to suppress the speech of the corporate employees. How far are you willing to take that line of reasoning? What if the government aids you in other ways? What if you're a government employee? What if you receive tax breaks? Student loans? What if your industry enjoys tariff protection? Diplomats enjoy diplomatic immunity–do we get to suppress their speech as well? Why do you single out recipients of limited legal liability for speech suppression?

And I note that this hypothetical is rather far from what is in practice now. In practice, regardless of your willingness to accept liability, no one can buy cigarette TV ads now without facing fines or prison time.

Note that I have no objection to making people liable for any fraudulent claims that they make (whether they make them as an individual or as a corporation). Your beef seems to be with corporate liability laws, with which I probably agree with you. But your distaste is such that you're willing to advocate the suppression of the speech of corporate employees.