On paper, the potential for a conflict of interest seems obvious: ABC News, the host of next month’s high-stakes presidential debate, falls under the purview of a top corporate executive at Disney who happens to be longtime friends with the Democratic nominee. The executive, Dana Walden, first met Kamala Harris in 1994. Their husbands, Matt Walden and Doug Emhoff, have known each other since the 1980s. The Waldens — “extraordinary friends,” per the vice president — have donated money to Ms....