He probably has “technical advisors” with Crip and Blood connections - who remember perfectly well what happened to the technical advisors on the movie “American Me” when they disclosed too much about the Mexican Mafia and its operations.
I don’t blame Singleton to be worried about his own safety but then he should have NEVER made “Snowfall” in the first place rather than present a completely distorted reality that writes out the existence of the Crips & Bloods.