William Theisen, the former artistic director of Skylight Opera Theatre whose June firing ignited controversy and protests, has canceled his agreement to direct four shows in the company’s upcoming season. “Theisen backed out because the company’s managing director, Eric Dillner, fired two of his cast members,” who had “supported Theisen and criticized Dillner in comments on Facebook and on blogs.” Theisen’s withdrawal was followed by a cascade of artist departures.