The chief justice presides because the vice president is the beneficiary, so to speak, of the removal of a president. Otherwise, the VP presides over an impeachment trial. I don't think Roberts would have any powers other than those the Senate affords him. They make the rules for an impeachment trial and his job would be to ensure they are followed. If Mitch wants a sham, I don't think there is any way of stopping it.
Thank you. Well said.
