The Montreal International Jazz Festival closed the production, a “theatrical odyssey based on slave songs,” after only a handful of performances in the wake of an outcry over a majority-white cast portraying black slaves. Only two of the seven people in the show, directed by Robert Lepage and starring Betty Bonifassi, were black. While critics of the show have welcomed the closure as a necessary cultural reckoning, several leading theater directors in Quebec rallied behind Mr. Lepage this week, citing their concerns that closing a production by such an internationally acclaimed director could have a chilling effect on artistic expression in Canada. At least four theaters are proceeding with productions of “Slav,” even if that means braving protests.