True, Trump didn’t sue his ghost writer but he did try to cheat him. From the New Yorker:
Trump informed Schwartz that, as his ghostwriter, he owed him for half the event’s cost, which was in the six figures. Schwartz was dumbfounded. “He wanted me to split the cost of entertaining his list of nine hundred second-rate celebrities?” Schwartz had, in fact, learned a few things from watching Trump. He drastically negotiated down the amount that he agreed to pay, to a few thousand dollars, and then wrote Trump a letter promising to write a check not to Trump but to a charity of Schwartz’s choosing. It was a page out of Trump’s playbook. In the past seven years, Trump has promised to give millions of dollars to charity, but reporters for the Washington Post found that they could document only ten thousand dollars in donations—and they uncovered no direct evidence that Trump made charitable contributions from money earned by “The Art of the Deal.”