On Tuesday Richard Plepler, the chief executive of HBO, said he regretted that a show he described as a complex exploration into “the thin veneer of civilization” was announced with a brief news notice.
Mr. Plepler’s remarks echoed sentiments expressed by Casey Bloys, HBO’s programming president, who at the Television Critics Association press tour in July said the “Confederate” announcement was “misguided.”
Both HBO executives have expressed support for the concept of the series itself. Production on “Confederate” will not begin until after the final season of “Game of Thrones,” which will debut in the second half of 2018, at the earliest.
Mr. Benioff and Mr. Weiss, who are white, are developing “Confederate” with the married writer-executive producers Malcolm Spellman and Nichelle Tramble Spellman, who are African-American.
In an interview with Vulture in July, the series’ four creators said they expected the backlash but maintained that it was precisely the explosive nature of the material that made a speculative alternate history an ideal format in which to discuss it.
“One of the strengths of science fiction is that it can show us how this history is still with us in a way no strictly realistic drama ever could,” Mr. Weiss said. “It’s an ugly and a painful history, but we all think this is a reason to talk about it, not a reason to run from it.”
Mr. Spellman added: “I think people have got to stop pretending that slavery was something that happened and went away.”