It’s an ironic twist, for sure, that the best news Shari Redstone has gotten since she decided to sell Paramount Global arrived last week in the form of a credit downgrade. On the surface, of course, it is bad news indeed that S&P Global relegated the company’s $14 billion of net debt to junk bond status, which scares off investors and drives up borrowing costs. But there is a strange silver lining here for Shari, which might make it easier for her to sell National Amusements Inc., the Paramount parent company, to David Ellison, the scion of tech billionaire Larry Ellison and founder of Skydance Media, who now wants Paramount, too.