Bill Ackman said a settlement with Automatic Data Processing Inc. is “unlikely” as the activist investor defended his track record amid repeated attacks by the company’s management and board. The billionaire investor wouldn’t be willing to compromise and take just one seat at the human resources outsourcer, he said, given the fight that the current board has put up to resist his push for change. Ackman has put forward three nominees, including himself, for a shareholder vote next month.