First Amendment principles are clear: Public figures really are different when it comes to image control. It's one thing for an ordinary person to be able to control the use of her image. That makes both legal and economic sense, because as a private person you should be able to choose who gets to display and make a profit from what you look like. But when you have run for president and won and dominated the political conversation for the last five years, you should not be able to control the use of your image in a political context. Such censorship would detract too much from the valuable exchange of political ideas.
Imagine if the Democratic National Committee, not the RNC, were using Trump's image to convince voters to donate money to discourage Trump from returning to politics. We would all have the instinct that this should count as protected political speech. It would be bizarre if Trump could use his own image to promote his own candidacy but the other side couldn't use his image to take the opposite position.
The reason that Trump's argument against the RNC feels different is because, in some sense, the RNC is seeking to financially gain from Trump's image and name — to imply an endorsement where there is none.
Imagine if a for-profit company were trying to use Trump's image to sell its product. Then the legal landscape would change. Because celebrities count as public figures, paparazzi can take their pictures for publication by "news" outlets. But even if someone is a public figure, the law protects him from having his image used to sell Coke or Pepsi. That's why celebrities have to be paid for endorsements.
The RNC is not a for-profit entity, but it is in a loose sense using Trump's image and name for product endorsement of its candidates. Trump, who built much of his real estate pseudo-empire on the deployment of the name "Trump" as a brand, feels instinctively that this is wrong. If I owned a hotel, I couldn't just rename it the Trump Plaza — because Trump rightly owns that hotel brand. (We will leave for another day the question of whether I could do that if I were making a satirical political comment — like if I put the name Trump on a roach motel.)
And that's where Trump is on to something. The RNC is using Trump's name and image differently from the way the DNC would be. The RNC is implying to potential donors that Trump is endorsing its messages and the candidates it will support. And from Trump's perspective, that's just plain deceptive. He only wants the RNC to be able to use his name and image if the RNC is doing his bidding. If it isn't, that he doesn't want it to have his endorsement. Implying otherwise is deceptive and a lie.
You can fill in here your objection that Trump, king of the big lie in American politics, lacks the standing to object that the RNC is misleading people. I hear you.
Nevertheless, good principles should apply even to repugnant people. And the truth is that there is something troubling about a system that allows political parties to mislead donors about who is endorsing their requests for money.
That leads to a final and more serious problem: that political fundraising is generally categorized as a form of political speech and therefore is exempt from the laws that would ordinarily apply in the context of false advertising. The reason for that is the Supreme Court's embrace of the idea that in politics, the expenditure of money counts as a form of free speech. This theory has had a profoundly distorting effect on U.S. politics and limited the country's ability to regulate election financing. Almost no other country in the world agrees. But here we are.
If the RNC were using Trump's image to sell soap, the former president would have a legal case. But selling candidates is a different matter. Under existing law, Trump can't do anything about it. Maybe that should help us realize that we need an overhaul of how we think of money in politics.