Retaining or gaining new viewers wasn't the goal of that BTS session. It was just one person meeting her favorite actors from her favorite soap. Why can't that be enough?
I get what you're saying about Black viewers, as well as @lovemesomejoolery's comments about viewers in general. And I don't disagree with either statement. But again, this had nothing to do with viewers in general and everything to do with one specific viewer, who appeared to be thrilled to spend time with the actors.