Where is the Chief Justice? This is his job. Has he resigned as Chief? Acting Chief Justice Clarence Thomas can preside instead.
No, Roberts has decided (quite properly, IMO) that as Trump is not a sitting President is is not appropriate for a Supreme Court Justice to preside over such an event.
It’s not his job. Trump isn’t President.
This whole thing is a can of worms and opens up all kinds of Constitutional issues that can and will be debated on both sides