Billionaire Sumner Redstone can’t avoid a lawsuit challenging his removal of directors from the board of Viacom Inc. At least not yet, a judge ruled. The decision by Delaware Chancery Court Judge Andre Bouchard allows the case by ousted Viacom director Fred Salerno to go forward with a trial scheduled for October, the same month two other courts will hear cases over recent decisions by the media mogul. “What’s at stake here is nothing less than the governance of a multibillion-dollar company,” Bouchard said. “My focus is whether a 90-year-old man in a rapidly declining state of health had the mental capacity” to take the actions attributed to him. Bouchard is overseeing one of two lawsuits brought by former members of Redstone’s inner circle since May as the billionaire seeks to reassert control over his $40 billion empire by rearranging Viacom’s management and removing two people from a family trust that will control the company.