The most biased members of the media do not necessarily come straight from politics.
Journalism schools provide even greater insulation and incubation for left-wing ideas than do campaigns. So, whether Jake Tapper or Christiane Amanpour or Anderson Cooper moderates this presidential debate, it probably does not make a difference — the CNN representative would push issues (abortion, “democracy,” Trump’s legal issues) favorable to Biden and suppress issues (inflation, illegal immigration, international disorder) favorable to Trump.