I think that the redeeming grace in this is that Biden, who is arguably no longer mentally competent to be President, will have to make semi-coherent arguments, and Trump can point out the problems in Biden’s answers. All will be able to see. It will be tough for Biden regardless of who the moderators are. And I think that Tapper at least will ask a question or two that will require a reasoned defense of his policies.
One of the problems is that, if Biden does really, really badly to the point that his mental incapacity is obvious, the 25th Amendment might be invoked with support from the Democrats so that a substitute nominee can be put in place. For Trump it is perhaps better for Biden to be the nominee than to have a surprise entrant at the last minute.