Famed Massachusetts mill owner Aaron Feuerstein has this message for his friend and embattled media executive Sumner Redstone: hang in there. “As long as he is succeeding, and as long as it’s profitable, I don’t see why he should step down,” Feuerstein said in an interview of Redstone, the 92-year-old executive chairman of both Viacom Inc and CBS Corp who faces renewed questions over his fitness to lead.