I had the exact same thought! The timeline is almost puzzling: • Episode "Sponsored Content" (s19e08), in which advertising disguised as news is first mention

I had the exact same thought! The timeline is almost puzzling: • Episode "Sponsored Content" (s19e08), in which advertising disguised as news is first mentioned, aired on November 18. • The Ofcom report was published on November 20. Maybe the report was announced early, Trey Parker and Matt Stone heard about it and got the idea from there?